Elegant and perfect for entertaining, these Gruyere, Mushrooms, & Caramelized Onion Tarts are easy and BIG on flavor!
I am so PROUD of this recipe! It’s elegant, sexy, and the perfect appetizer to share with your guests this spring! Flaky, golden brown puff pastry topped with crimini mushrooms sauteed in butter, caramelized onions soaked in balsamic vinegar, a touch of garlic powder, and Applewood smoked gruyere cheese…it doesn’t get any better than that!The flavors in these tarts are bold and in your face! They invoke an essence of elegance, and impress my guests every time I make them. The best part? RIDICULOUSLY EASY! With just a few ingredients making these tarts a head of time before your dinner party makes life so much easier. To make these gruyere, mushrooms, & caramelized onion tarts I start off by browning some crimini mushrooms for about 5 minutes. Then I caramelize the onions in my cast iron skillet. The whole process takes about 10-15 minutes, and I add some sugar to speed it along. I then add some balsamic vinegar to de-glaze the pan and let the onions soak in it.
From there I combine the onions and mushrooms, season with salt, pepper, and garlic powder and allow it to come to room temperature before tossing with the gruyere cheese. For my puff pastry, I leave the sheet cold just until it’s ready to bake. Achieving a flaky, buttery crust is key in the success of this recipe!
You won’t be able to keep your hands off these tarts! Grab the recipe below.
- 2 tablespoons salted butter, divided
- 6 ounces crimini mushrooms, sliced
- 2 medium yellow onions, thinly sliced
- 1 teaspoon dried thyme
- 1 tablespoon sugar
- 2 tablespoons balsamic vinegar
- 1 teaspoon garlic powder
- salt and pepper, to taste
- 4 ounces grated applewood smoked gruyere cheese
- 1 package frozen puff pastry, (I used Pepperidge Farm® brand)
- 1 egg, lightly beaten
- Heat 1 tablespoon of butter in a large cast iron skillet over medium heat.
- Add the mushrooms and saute for 5 minutes until tender. Remove and set aside.
- Heat the remaining tablespoon of butter and saute the onions for 5 minutes.
- Add the dried thyme and sugar and continue to cook for 10-15 minutes on medium low heat stirring the onions every 5 minutes so they do not burn.
- Add the balsamic vinegar to de-glaze the pan and allow the onions to soak it in.
- Turn off heat and add the onions to the mushroom mixture.
- Season with the garlic powder and salt and pepper to taste. Stir to combine.
- Set aside and allow to cool to room temperature.
- Add the gruyere cheese and mix well.
- Preheat the oven to 400 degrees F.
- Cut the puff pastry sheet into 8 squares. Make sure the puff pastry is cold before proceeding. Brush the beaten egg on the squares.
- Place a tablespoon of the caramelized onion and mushroom mixture in the center.
- Bake for 20-25 minutes, until crisp and golden brown.
- Cool slightly before serving.