Caramelized Onion and Baby Bella Panini Melt on paperThis is the story about how I bought a loaf of bread and made one of the best sandwiches of all time.

This story is a tale of how onions sizzle and sweeten. How baby bellas brown to perfection. And the way my heart pitter-patters when melted cheese stretches between two halves of a sandwich.

Alight! Now i’ve got your attention.

The leading characters: Ms. Sweet Caramelized Onions and Mr. Meaty Baby Bella Mushrooms.

Oh and of course the real reason we’ll all be scarfing down loads of these paninis. Melty, ooey, gooey provolone cheese.

close up of mushroom panini meltThis sandwich is oozing with flavor. And don’t even think to not try it. Even if you’re not a mushroom person. You will be after this. You. will. be. after. this. Really.Caramelized Onions in saute panHere’s what the onions should look like after 20 minutes. After the first 5 minutes, add in the sugar. Continue to cook until the 20 minutes are up. Add the thyme, garlic and the Worcestershire sauce. Cook for another 2 minutes.sautéed onions and mushrooms in saute pan

Mushrooms after they’ve been cooked for 10 minutes. Next we add the red pepper flakes and black pepper. Add the flour and cook for 1 minute. Add the mushroom broth (or beef broth) one tablespoon at a time (4 tablespoons in total).

sautéed filling for panini topped with parsley

Sprinkle with parsley. Hear the sizzle. The butter as it slowly takes in the flavors of garlic and thyme. The touch of heat with the red pepper flakes. You want a bite. You know you do.

Lets make a panini!

bread with cheese, caramelized onion and mushrooms before grilling

Into the panini press it goes! Or in my case… my George Foreman. But that’s not really fun to say.

panini sandwich cut in half showing filling


Yield: 5 sandwiches

Caramelized Onion Baby Bella Panini Melt

Prep Time 10 minutes
Cook Time 40 minutes
Total Time 50 minutes

An easy to make caramelized onion and mushroom panini. Flavored with thyme, garlic, and red pepper flakes. Vegetarian/vegan friendly!


To make the caramelized onion + mushroom filling:

  • 2 tablespoons EACH: unsalted butter AND olive oil
  • 1 and 1/2 large onions (or 2 medium) sliced into 1/4 inch thick slices
  • 1 tablespoon sugar
  • 1/4 teaspoon thyme
  • 1 - 2 tablespoons minced garlic
  • 1 teaspoon Worcestershire sauce
  • 8 oz fresh baby Bella mushrooms, sliced into 1/4 inch thick slices
  • 1/2 teaspoon black pepper
  • salt to taste
  • 1/4 - 1/2 teaspoon red pepper flakes (or more to taste)
  • 1 teaspoon flour
  • 1/4 cup mushroom broth (or beef broth)
  • 2 tablespoons minced parsley

To make the panini:

  • 5 - 1 oz. slices provolone cheese, cut in half
  • 10 slices of fresh french bread
  • Cooking spray


    1. To make the caramelized onion + mushroom filling:
      Preheat a large skillet on medium heat. Add the butter and olive oil. When the butter is completely melted, add the onions. Let the onions cook down for 5 minutes. Add the sugar and let the onions continue to cook for 15 more minutes. Stir periodically allowing the onions to brown but not burn. Add the garlic, thyme, and Worcestershire sauce and let cook for another 2 minutes. Add the mushrooms. Stir and mix everything together until well incorporated. Continue to cook for another 10 minutes. Add the black pepper, red pepper flakes, and flour. Cook for 1 minute. Add the mushroom broth (or beef broth) in 1 tablespoon at a time. Wait until the onion/mushroom mixture absorbs the liquid before adding the next tablespoon. Once the 4 tablespoons are added, turn off stove remove from heat and add the parsley.
    2. To make the panini:
      To assemble the sandwich, place a halved slice of cheese on a piece of bread. Add desired amount of filling and top with another halved slice of cheese and another slice of bread. Spray one side of the sandwich with cooking spray and place that side down on the panini press. Spray the other side and press sandwich for 3 - 4 minutes of until the preferred toast level is achieved.

Have you made this recipe?

If you enjoyed this recipe, please consider leaving a ⭐️⭐️⭐️⭐️⭐️ rating and a comment below. You can also share a picture on Instagram with the hashtag #LITTLESPICEJAR, I'd love to see what you made!