Caramelized Onion Puff Pastry Bites with Gruyere and Mushrooms
Caramelized Onion Puff Pastry Bites with sautéed crimini mushrooms, balsamic caramelized onions, and applewood smoked gruyere cheese. The perfect little appetizers! They’re made with puff pastry and take no time at all to whip up. They are the perfect appetizers to serve your guests this holiday season!
Snappetizers!
Buttery, flaky puff pastry topped with balsamic caramelized onions, sauteéd mushrooms, a hint of garlic, and a smoked gruyere cheese bomb mixed right in.
These caramelized onion bites are a game-changer for me. They’re perfect to serve your Thanksgiving, Christmas, and New Years guests before a big dinner. Also, they totally look fancy schmancy, but nobody really needs to know that the caramelized onion and sauteéd mushroom filling can be made a couple of days ahead of time.
I’ve had readers tell me that these easy caramelized onion puff pastry bites flew out of the oven and right onto the guests’ plates! They are always a hit when we make them for parties, and with a sprinkle of parsley or some fresh thyme, the scent of these caramelized onion bites is UNREAL.
How to make caramelized onion bites:
Ingredients for caramelized onion tarts (or tartlets)
- Butter and oil: We’ll use these ingredients to saute the mushrooms and the onions for the recipe. I like to use a high-heat oil such as avocado, sunflower, or vegetable to cook the onions and mushrooms.
- Mushrooms: I prefer to use small crimini or baby bella mushrooms, but button mushrooms, shiitakes, or a medley of mushrooms would also work for this recipe.
- Yellow onions: slice the onions thinly so that the caramelizes quicker in the pan. We’ll cook them down in a large skillet until they are tender and delicious.
- Dried or fresh thyme: We’ll use some type to flavor the onions.
- Seasonings: I keep things pretty simple. You’ll want some sugar to help the caramelization process of the onions; you’ll also need kosher salt, black pepper, and some garlic powder.
- Balsamic Vinegar: The syrupy vinegar cooks down with the onions and creates a balsamic glaze in the pan. This not only gives the onions a more delicious color, it also helps boost the sweetness which pairs beautifully with the nutty gruyere cheese.
- Gruyere Cheese: I like to use applewood smoked gruyere for this recipe as the smoky flavor pairs well with the sweetness of the jammy onions and the natural umami or mushrooms. You can also use regular gruyere or other economical options like white cheddar.
- Puff Pastry: For this recipe, you’ll need a box of frozen puff pastry. To make the process smoother, I like to thaw the puff pastry in the refrigerator overnight according to the package directions. I’ve never been able to get puff pastry to defrost quickly, so definitely plan ahead for this recipe.
- Large egg: This is for the egg wash! It just gives the puff pastry a beautiful sheen when it comes out of the oven.
How to make caramelized onion puff pastry bites:
- Start with the mushrooms. We’re going to start by sautéing the mushrooms in a few tablespoons of oil for 4-5 minutes. Once they start to brown, remove them to small bowl.
- Caramelize the onions. Add the remaining butter to the pan. Once it melts, add the onions. Let them hang out in the pan for 5 minutes. Remember to use a cast iron or stainless steel skillet. You also want to avoid using a nonstick skillet as the onions won’t caramelize. After the 5 minutes, season ith sugar and thyme. Now crank the heat down to about medium-low, and cook for a total of 25 minutes. Keep checking on them every 5-10 minutes, and give them a stir to keep them from browning too quickly. Drizzle the balsamic to help deglaze the pan, and when it’s all been soaked up, you can turn off the stove. Once the onions have cooled slightly, add them to the mushrooms and season with a little garlic powder, salt, and pepper.
- Store or use right away. Let your filling come to room temperature, you can store it in an air-tight container for up to 48 hours in the refrigerator. If you decide to make the filling ahead of time, zap it in the microwave to bring it back to room temp before continuing with the recipe instructions. Mix in the gruyere cheese and combine well.
- Make the bites. Cut the puff pastry sheet into small squares or rectangles using a pizza cutter or a sharp knife. I cut mine into 2-inch squares. Lay a piece of parchment paper on a large baking sheet. Place the squares on the prepared sheet pan. Brush them with a beaten egg using a pastry brush. Drop about a tablespoon of caramelized onion mixture on each puff pastry square.
- Bake: bake the caramelized onion puff pastry bites in the preheated oven until they are crisp and golden brown. Let them cool slightly before serving. Top with fresh parsley or thyme for a little color!
Look at each of those puff pastry layers and how perfectly they separate from each other. It’s like taking a bite out of 10 potato chips at the same time, only less crunchy, and more buttery. Okay, so not like a potato chip at all, really.
Caramelized onion puff pastry bites are going to make your holidays more amazing. The garlic, the mushrooms, the caramelized onions, and the smoky gruyere.
If you like this caramelized onion bites recipe, you might also like:
- Chicken Puff Pastry (Chicken Patties)
- Easy Puff Pastry Twists with Za’atar
- Crispy Feta Cheese Filo Pastry Spirals
- Greek Spinach Puffs
- Hot Honey Cranberry Goat Cheese Balls
Caramelized Onion Puff Pastry Bites with Gruyere and Mushrooms
Caramelized Onion Puff Pastry bites with sautéed crimini mushrooms, balsamic caramelized onions, and applewood smoked gruyere cheese. The perfect little appetizers! They’re made with puff pastry and take no time at all to whip up! These are the perfect appetizers to serve your guests this holiday season.
Ingredients
- 4 tablespoons salted butter, divided
- 2 tablespoons vegetable oil, divided
- 5-6 ounces crimini or button mushrooms, sliced
- 2 medium yellow onions, thinly sliced
- 1/4 teaspoon dried thyme
- 1 tablespoon sugar
- 1 1/2 tablespoon balsamic vinegar
- 1/4 teaspoon garlic powder
- salt and pepper, to taste
- 4 ounces grated gruyere cheese (I used applewood smoked gruyere)
- 1 package (1 pound) frozen puff pastry, thawed
- 1 egg, lightly beaten
Instructions
- MUSHROOMS: In a large cast iron skillet over medium heat, heat 1 tablespoon of oil along with 1 tablespoon of butter. When the butter melts, add the mushrooms and sauté for about 5 minutes until golden and tender. Remove and set aside in a medium bowl.
- CARAMELIZE: Heat the remaining 3 tablespoons of butter along with 1 tablespoon of oil and sauté the onions for 5 minutes. Add the dried thyme and sugar and continue to cook for 25 minutes on medium-low heat. Make sure to stir the mixture every 5-10 minutes. If the onions are caramelizing too fast, turn down the heat a little more.
- DEGLAZE: Add the balsamic vinegar to deglaze the pan, allow the onions to soak it all in. Turn off heat. Add the onions to the mushroom mixture. Season with the garlic powder and salt and pepper to taste, stir to combine.
- MAKE AHEAD: Allow to cool to room temperature. The mixture can be kept in an air-tight container in the fridge for up to 48 hours. Allow to come to room temperature before proceeding. Add the gruyere cheese and mix well.
- PREP FOR BAKING: Position two racks in the upper and lower thirds of the oven. Preheat the oven to 400º F. Line 2 baking sheets with parchment paper or silicone mats.
- FILL: Using a sharp knife or a pizza cutter, cut the puff pastry into 2-inch squares and place them on a lined baking sheet. Make sure the puff pastry is cold before proceeding. If not, allow it to rest in the refrigerator for 10-15 minutes before proceeding. Using a pastry brush, brush the beaten egg on the squares. Prick the puff pastry using a fork in the center. Place a tablespoon of caramelized onion mixture in the center.
- BAKE: for 20-25 minutes, rotating the pan halfway in between until crisp and golden brown. Let cool slightly before serving.
Notes
- Make sure the puff pastry is cold when it goes into the oven. If at any point it becomes soft, allow it to rest in the refrigerator for 15-20 minutes or until it firms up again. Do not open the oven door during the first 10 minutes of baking time. Frequently opening the oven may cause the puff pastry to not 'puff up'.
- Mozzarella or gouda cheese may be used to replace the gruyere. I really like the smoky flavor of applewood smoked gruyere with these bites.
- If you've prepared the caramelized onion mixture ahead of time, you can zap it in the microwave for 30 seconds to bring it back to room temperature quickly.
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I made these for a baby shower and they were so good, I am making again for the baby’s first birthday and some to bring along next weekend with friends. you wont be disappointed!
Amazing recipe,
Easy to make
Taste Great
I made these for a Christmas party and they were excellent, everyone loved them.
Versatile and delicious!
Made this and everyone loved it. Will make it again.
Hi Marzia, can i make these one day ahead?
I’ve made the filling a day ahead and then assembled the day of and that’s worked out fine. As far as assembling and baking ahead of time goes, for best results I suggest preparing the day of. I find the puff pastry looses a bit of it’s magic when you reheat it.
HI Marzia,
I was wondering what you think of how this appetizer travels? I notice one comment below that says it travels well. I was actually planning on making everything and traveling to a friends with it (about 30 minutes away). Does it serve well at room temperature or should it be warm? If I don’t get to make this recipe for my friend’s party, I’ll definitely make it at home. thanks!
Yes, you can serve this at room temperature if you’d like. I personally prefer them a little warm so I suggest reheating them in a 300ºF oven for 10-15 minutes before serving. If you’re making these before traveling with them I suggest making them ahead of time so that they have a chance to cool before you cover/transport them. If you cover them right out of the oven the puff pastry may lose some of that beloved crispness. Hope everyone at the party enjoys them! 🙂
Can this be made with phyllo instead of puff pastry?
Unfortunately phyllo is not a good substitute for the puff pastry.
Omgosh these are sooo good! I used mozzarella and queso fresco cheese. Keeping this recipe thanks for sharing!1
These are delicious!!! I wanted to make them ahead of time so I made the filling and cooled it to room temperature as you suggest. I rolled out the thawed puff pastry slightly to 12×12 inches and cut it into 24 pieces. I fit each piece of pastry into a mini muffin pan to make mini crusts and placed the filling to the top of each cup, I then covered the pans with plastic wrap and then foil and froze them overnight. I just popped them out the next day and into a freezer bag for later use. When ready to bake I simply place the frozen cups back into the mini muffin pans and bake for 20 minutes at 400 degrees.
I’ve made these twice now and they’re so good. I’m always looking for party food to make ahead, and these tarts are perfect.
Can I add a little apple or pear?
Sure! I do suggest cooking the pears or apples to draw out that moisture before using them in the filling, though.
Absolutely delicious. I made this recipe today and took it to a dinner and it was a huge hit. Everyone loved it and wanted the recipe. The only thing I changed was that I used fresh garlic instead of powder. Fabulous, honestly
How far in advance can I assemble and put in fridge . Want to do this ahead of time so I can just put in oven when guests arrive?
The filling can be prepared a day in advance. I haven’t tried assembling these ahead of time and baking later, but my best guess is it would be okay to do about 2-3 hours ahead.
Mel, I have been making these for years now and I completely assemble them and IQF them on parchment paper covered cookie sheets. I then store them in layers on parchment in a 15”x10”x2” plastic food service container. I can get 4 layers in a container. I pull a layer out at a time and bake it on the same parchment and no need to defrost. I serve these at Thanksgiving and Christmas and any other fancy party we might have. Always a huge hit and all the work is done way in advance. Using the parchment also means no pan to wash after! I usually double this to have as much on hand as possible. I have a second freezer, so that really helps. They keep more than 3 months. I have also had extra filling and frozen that too. I am not a balsamic vinegar fan so I substitute Sherry Vinegar and use half the amount of sugar since I use sweet onions. Cheers!
Exceptional! My “go to” appetizer. Everyone loves them.
I am planning on making these for a 4th of July party and am thinking about using a star cookie cutter. Do you think that will work? Of course I would score them along the perimeter.
That sounds like a fun idea! Hmm. I think the star shape could work, I’m just worried about the tips of the star and if they’d burn in the amount of time it takes for the puff pastry to cook all the way through. I suggest doing one test pastry and see how it works out 🙂
Marzia, I took your advice and did a test using a star cookie cutter for the 4th of July. The first star (about 3″) was too big in that the pastry to filling wasn’t right (too much pastry). I then tested a star that was about 2 1/4″. It worked perfectly and the star bites were a big hit! I was sure to score inside the stars and put the filling in the middle. Thanks for a great recipe!
Excellent! Glad it worked out. Thanks for reporting back as I’m sure others may be interested in using a different shape as well! 🙂
I can only find hickory smoked gruyere and regular. No applewood smoked. Which should I use, Hickory smoked or regular? thanks
Either would work! Totally your call!
I made this as a pizza. I used store bought pizza dough. I baked the dough for about 10 minutes before I added the mushroom mixture. I then put olive oil and fresh garlic on the crust topped with the mushroom mixture and baked for 20 minutes. It was delish.
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Filling is SO GOOD but even following the directions exactly, the puff pastry was too much carb and super puffy – the topping got lost in it! I made it again an filled mini phyllo dough cups and they were perfect for us. Also very good on simple crostini or a cracker.
This recipe is soooo good. The taste the texture is perfect. Some of my friends like only cream cheese so I switched and add 1/2 tsp of cream cheese at base and the rest of the filling on top. They loved li!!!!i think this is such a perfect recipe that it simply adapts .
I made these for Thanksgiving this year, this recipe was a big hit with everyone. I got compliments from all of my guests. This recipe will be a Thanksgiving tradition from now on.
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Has anyone tried crescent roll dough rather than puff pastry?
Where can you buy crescent dough?
Elizabeth-crescent rolls are in the refrigerator section of the grocery store by the rolls of biscuits.
Can I freeze the mixture ahead of time? Or will it stay in the fridge for 3 days?
It’ll be fine in the fridge for 3 days!
Made these last night for a NYE party. They were tasty, even though I forgot the garlic powder and balsamic (doh!). Like another commenter, though, they were rather too “puffy — the edges did not rise up around the filling like in the pics, and it felt like they should have more filling in them. Should I maybe score the dough? Puff pastry is the bomb but can be a little tricky. Thanks for the delicious recipe, I will add this to my repetoire!
Just a thought: You might have dragged the knife blade through the puff pastry dough. If you cut straight down the edges won’t be sealed and it will allow the dough to puff up better.
Made this recipe for a party tonight. I actually added shaved ribeye on one side of pastry raw with steak seasoning on it. Cooked perfectly! I’m not sure if they’ll make it there because we keep eating them. Are there any suggestions of a dip I could serve with them?
Let me start off by saying, I’m a horrible cook. That being said, these tarts are so easy to make, the instructions really make the prep process so much easier.
I have made these tarts at least 4 times and, by popular demand, I am making them for another party tomorrow night. I would encourage everyone out there to make them at least once. 5 stars!!
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Has anyone tried making these in the mini pastry shells? I have a jar of bacon jam that I love and was thinking a little of that in the shell with the onion mushroom mixture on top and topped with the parmesan. What do you think?
Bacon Jam…. what is that? It sounds wonderful.
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