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Caramelized Onion Tart with Gruyère and Thyme Recipe

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4 from 90 reviews

  • Author: admin
  • Total Time: 1 hour 10 minutes
  • Yield: 8 servings 1x

Description

This Caramelized Onion Tart with Gruyere and Thyme is a savory and elegant dish that combines the sweetness of deeply caramelized onions with the nutty richness of Gruyere cheese, all infused with fragrant fresh thyme. Perfect as a sophisticated appetizer, brunch item, or light dinner, this tart features a flaky pie crust and a creamy custard base accentuated by balsamic vinegar for a subtle tang. It yields 8 generous servings and takes just over an hour to prepare and bake, making it an impressive yet approachable recipe for any occasion.

Ingredients

Scale

For the Pie Crust

  • 1 pie crust, preferably homemade (blind baked)

For the Filling

  • 4 large onions, sliced into ¼-inch rounds
  • 1 tablespoon sugar
  • ½ teaspoon kosher salt
  • 1½ tablespoons balsamic vinegar
  • 2 tablespoons fresh thyme, chopped (or 2 teaspoons dried thyme)
  • ¼ teaspoon freshly ground black pepper
  • ¼ cup heavy cream
  • 1 cup Gruyere cheese, grated

Instructions

  1. Blind Bake the Pie Crust: Preheat the oven to 375°F (190°C). Place the pie crust in a tart pan, prick the base with a fork, line with parchment paper, and fill with pie weights or dried beans. Bake for 15 minutes, then remove the weights and parchment and bake for another 5-7 minutes until the crust is lightly golden. Remove from oven and set aside.
  2. Caramelize the Onions: In a large skillet over medium heat, add a splash of oil or butter and the sliced onions. Cook slowly, stirring occasionally, until the onions become soft and translucent, about 15 minutes. Add the sugar and kosher salt to help with caramelization. Continue cooking for another 15 minutes, stirring more frequently, until the onions are deeply golden brown but not burnt.
  3. Add Flavorings: Stir in the balsamic vinegar along with the fresh or dried thyme and black pepper into the caramelized onions. Cook for 2-3 minutes more, allowing the vinegar to reduce and coat the onions, infusing the tart filling with a rich depth of flavor. Remove from heat and let cool slightly.
  4. Prepare the Custard Mixture: In a bowl, whisk together the heavy cream and the grated Gruyere cheese until combined.
  5. Assemble the Tart: Spread the caramelized onion mixture evenly over the pre-baked pie crust. Pour the cream and Gruyere mixture evenly on top. Ensure the filling is distributed smoothly for even baking.
  6. Bake the Tart: Return the tart to the oven and bake at 375°F (190°C) for 25-30 minutes, or until the custard is set and the top is golden brown with bubbling cheese.
  7. Cool and Serve: Remove the tart from the oven and let it cool for about 10 minutes before slicing. This allows the filling to set further for cleaner slices. Serve warm or at room temperature.

Notes

  • For a flakier crust, use a homemade pie crust with cold butter for the best texture.
  • The balsamic vinegar adds a subtle tang and depth; do not skip for best flavor.
  • Gruyere cheese can be substituted with Emmental or a similar melting cheese if unavailable.
  • Leftover tart can be refrigerated and gently reheated in an oven or toaster oven.
  • This tart pairs beautifully with a crisp green salad or a light white wine.
  • Prep Time: 20 minutes
  • Cook Time: 50 minutes
  • Category: Appetizer
  • Method: Baking
  • Cuisine: French

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Find it online: https://a-tale-of-two.com/caramelized-onion-tart-with-gruyere-and-thyme-recipe/