Rockin’ Sweet Onion Mushroom Swiss Burgers

Learn how to make the BEST diner-style sweet onion and mushroom swiss burgers! The burger patty is juicy and perfectly seasoned, but it’s the mushrooms and onions really take it over the top! Top it off with swiss cheese, and you’ll see why it’s so addicting!


Now, this is a story about how my life got turned upside down!

Okay, I’m a tad bit dramatic.

Maybe it’s just a story about how I discovered the best mushroom swiss burger? Or perhaps there isn’t mush (excuse me, I mean much) to the story at all and it’s just rather a happy little miracle that happened one evening when I asked to have grilled sweet onions added to my regular order of mushroom swiss burgers. By the way, I apologize for that horrible pun! I don’t know what came over me.

Shout out to my favorite local burger joint (Stanton’s City Bites [1]) for inspiring today’s tasty burger recipe. I know not everyone plays on team mushroom, but these burgers are absolutely ADDICTING if you do. And it’s cool if you don’t root for the ‘shroom team. Just omit them and carry on with the rest of it if you wish because there’s still grilled sweet onions and an incredibly delicious, perfectly seasoned beef patty that just crumbles in your mouth to be had. Top it with arugula if you’re extra fancy or leave it off for a more hole-in-the-wall burger joint feel.

Your burger, your call.


Over the last eight months, I’ve made these mushroom swiss burgers more times than I care to put out there on the interwebs.

You know, to make sure the seasonings were just right. That the mushrooms weren’t overcooked and that the onions had adequate time to hang out and melt into this beautiful oniony jam that’s both sweet and salty. Just the most perfect thing to top your burgers with. That sort of thing.

I’ll admit, the burger I enjoy at SCB isn’t as heavily seasoned with garlic and onion as the one I’m sharing today, but I think the extra hint make this one extra special.

That first bite: It’s that perfectly seared meat patty with all those brown almost crunchy bits, but it’s still juicy and crumbly on the inside then come the mushrooms that are grilled on a flat top, diner-style and finally it hits you. The sweetness from the onions, immediately followed by that generous pinch of salt and all of that is wrapped up with melty swiss cheese on a butter toasted brioche bun.




Selecting the meat for our mushroom Swiss burgers:

  • First thing first, we need the right grind of beef. For a good, juicy burger you want to go with something like 80/20 or 85/15. I usually go with that latter when I’m making homemade burgers because 20% fat does sometimes feel extra indulgent to me, personally. Second, I suggest getting a ‘hamburger grind’ if possible. This is a little chunkier than regular ground beef.
  • Secondly, when you’re forming the patty, try to work the meat as little as possible. Just divide the meat into four equal portions. Here’s where a kitchen scale will be super handy! That way you can weigh it to make sure they’re all the same. When you’re ready to form the patty, make a ball with the ground beef (gently, please) and place it in between two sheets of wax paper or plastic wrap and then press down using a spatula or a small concave lid. <— This is how they do those fancy diner burgers — only they do this on a hot griddle. I’m chicken, and I prefer to do it away from the heat source!


The seasoning for our mushroom Swiss burgers:

This is where that magic happens! Nothing is worse than a burger that’s been underseasoned. Seriously, it’s such a whomp. You’ll notice I’ve already had you form the patties before seasoning them. That’s because we’re making diner-style burgers and the seasonings are seared onto the meat rather than stuffed into them. We’ll need just four simple ingredients:

  • Garlic powder
  • Onion powder
  • Salt
  • Pepper

Now we’ll set aside about a teaspoon of this seasoning to use on our mushrooms, and the rest of it gets sprinkled on both sides of the burger patties. That way when we place them on the grill, the seasonings flavor every inch of that burger patty and pack on that flavor!


A few tips to make the best mushroom Swiss burgers:

  • For the onions: I like to let these onions hang out on low in the pan until they start to brown and sweat down. But this takes time and it may not be everyone’s cup of tea! You can certainly just cook the onions for 10-15 minutes until they’re soft on the outside but still have a bite to them. To make them the way I like for these burgers, it’ll take you about 50 minutes. BUT the good news is you can do this up to 3 days in advance!
  • For the mushrooms: I used cremini (or baby Bella) mushrooms for my burgers, but you can use shiitakes or even button mushrooms if you’d like. No wrong answer here!
  • For grilling outdoors: once you place your burgers on the grill, let them hang out for a bit before you start moving them around. This will allow them to develop a crust so that when you do go to flip them, they don’t give you a heart attack by crumbling all over the place!
  • For cooking indoors: I suggest using a cast iron skillet for these or a flat top if you’ve got one. It’ll allow your burgers to get that same amazing sear that you would from grill grates. Not gonna lie, I slightly prefer cooking burgers indoors to the outdoor kind!

And there you have it, these mushroom Swiss burgers topped with homemade sautéed sweet onions are a piece of my heart. Serve them with tons of waffles fries and watch the family come running for dinner!

Once you taste these, you’ll see why I could have one every day of the week!


Rockin’ Sweet Onion Mushroom Swiss Burgers

Learn how to make the BEST diner-style sweet onion and mushroom swiss burgers! The burger patty is juicy and perfectly seasoned, but it’s the mushrooms and onions really take it over the top! Top it off with swiss cheese, and you’ll see why it’s so addicting!

Did you make this recipe?
Leave a review » [3]


Caramelized onions:

  • 1 ½ tablespoon oil
  • 1 jumbo onion, thinly sliced (2 ½ cups)
  • 1 teaspoon sugar
  • ¾ teaspoon kosher salt

Swiss mushroom burgers:

  • 1 ¼ pounds ground beef (80/20 or 85/15)
  • 1 tablespoon garlic powder
  • 1 teaspoon EACH: kosher salt, black pepper, and onion powder
  • 1 tablespoon olive oil
  • 8 ounces sliced baby bella mushrooms
  • Swiss cheese, for topping (or any other cheese you like)
  • 4 burger buns
  • arugula, for topping (totally optional)


  1. ONIONS: heat the oil in a large skillet over high heat. Add the onions and allow them to sizzle for about 5 minutes stir as required so nothing sticks or burns. Season the onions with the sugar and salt. Lower the heat to medium-low, and all the onions to cook for 25-45 minutes stirring every 7-10 minutes (about every 5 minutes near the end) so nothing sticks. I like the onions around the 45-minute mark, but how far you take the onions is entirely up to you. MAKE AHEAD: at this point, you can remove the onions to a container, allow them to cool to room temperature and refrigerate them for up to 3 days!
  2. PATTIES: In a small bowl, combine the garlic powder, salt, black pepper, and onion powder; set aside. Divide the ground beef into 4 equal portions. Form into a round ball shape. Grab 2 pieces of plastic wrap and place one sheet of plastic wrap on a flat surface and place the meat ball on top, followed by the second sheet of plastic wrap. Using a concave lid, or even a large flat spatula, press the ball down into a flat patty. Set aside 1 teaspoon of this seasoning and use the remaining to season the patties (on both sides) evenly.
  3. MUSHROOMS: Prepare the grill (if you’re grilling outdoors.) While the grill is heating, heat a large sauté or cast iron pan over medium-high heat. Add the oil and the mushrooms to the skillet and allow them to cook for 2-3 minutes. When the mushrooms start browning, season them with the reserved teaspoon of seasoning and toss. Remove from heat into a bowl or a plate.
  4. COOK + ASSEMBLE: Cook the patties on the same skillet (or outdoors) for roughly 3-5 minutes per side (indoors) it may take a little longer on an outdoor grill or until it reaches your desired doneness. When the burgers are almost done, lay the Swiss cheese over them and allow it to melt. Remove to a plate when done. You can also toast the buns with just a brush of oil if you’d like. When ready to assemble, place the burger patty on the bun and top with the sautéed mushrooms, onions, and a handful of arugula if you want a little freshness!

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