Go Back
Print Recipe
5 from 1 vote

Mushroom Tart with Caramelized Onions and Thyme

This mushroom tart with caramelized onions and thyme is one of my favorite puff pastry appetizers. It's a quick and easy brunch recipe!
Prep Time20 mins
Cook Time1 hr 20 mins
Total Time1 hr 40 mins
Course: Appetizer or Main
Cuisine: American
Keyword: brunch, caramelized onions, mushroom tart, party appetizers, savory tart
Servings: 6 -8
Author: Hip Foodie Mom, adapted from Amy Pennington


  • 3 tablespoons extra virgin olive oil
  • 2 large yellow onions cut into thin half moons
  • 1 teaspoon kosher salt
  • 2 to 3 cups mushrooms sliced; try to use cremini or baby portobello mushrooms
  • 5 to 7 sprigs fresh thyme leaves stripped and chopped
  • 2 to 3 teaspoons balsamic vinegar
  • 2 sheets frozen puff pastry defrosted but kept cool
  • freshly grated cheese: like Parmigiano-Reggiano or Gruyère


  • Heat the olive oil in a large sauté pan over medium heat. Add the onions and stir continuously until softened, about 8 to 10 minutes. Sprinkle in the salt, add the sliced mushrooms and continue stirring until the mushrooms release their moisture and the pan becomes more and more dry. When this happens, add half of the thyme and the balsamic vinegar and reduce the heat to medium low. Cook the veggies, stirring occasionally, until caramelized and golden, for about 20 to 25 minutes or so. Remove from the heat and set aside.
  • Preheat the oven to 350°F. Adjust the oven rack to the center position.
  • Unfold the sheet/s of defrosted puff pastry on a parchment-lined baking sheet. I used 2 so that my tart would be a little larger and just attached the puff pastry dough; you can just use 1 sheet if desired. Fold all the edges over to create the pretty border around your tart. Top the center of the rolled out puff pastry evenly with the onion, mushrooms, thyme mixture.
  • Bake the tart for about 25 to 35 minutes, until the pastry is golden brown and flaky. When there is about 3 to 5 minutes left, if you are adding the cheese, sprinkle on the freshly grated cheese and continue baking for the remaining time. Remove it from the oven, sprinkle the remaining thyme over the top, and let it cool for about 10 minutes before slicing and serving.


This recipe uses two sheets of puff pastry which creates a larger tart