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Top View of Caramelized Onion Tartlets Recipe on Wooden Table

Caramelized Onion Tartlets

With caramelized onion, fresh thyme, and Gruyere cheese these Caramelized Onion Tartlets have the same flavor profile as French Onion Soup, but with a buttery extra flaky crust.
Course Appetizer, Snack
Cuisine American
Prep Time 1 hour
Cook Time 1 hour 15 minutes
Servings 12 servings
Calories 329kcal



  • 2 1/4 cups all-purpose flour plus more for rolling out the dough
  • 1/4 cup Argo Corn Starch
  • 3/4 teaspoon salt
  • 1 cup unsalted butter chilled and diced
  • 3/4 cup ice-cold water plus more as needed


  • 2 tablespoons unsalted butter
  • 3 small-medium yellow onions peeled and thinly sliced
  • 1/2 teaspoon salt
  • 1/2 teaspoon black pepper
  • 1 clove garlic peeled and crushed
  • 1 teaspoon minced fresh thyme leaves
  • 2 large eggs
  • 1/4 cup heavy whipping cream
  • 4 teaspoons Argo Corn Starch dissolved in 1/4 cup cold water to make a slurry
  • 4 ounces Gruyere cheese shredded


For the Crust:

  • Whisk together the flour, corn starch, and salt, and then use a fork or pastry cutter to cut in the diced butter.
  • Adding 2 tablespoons of ice-cold water at a time, work in enough water so that it forms a dough and you can squeeze it into a ball.
  • Shape the dough into a disk, wrap it in plastic wrap, and refrigerate to chill, about 30 minutes to 1 hour. Or you can chill the dough for up to 3 days and let it sit at room temperature for about 15 minutes before rolling it out.

For the Filling:

  • Add the butter to a large, heavy-bottomed skillet over medium heat.
  • Once melted, add the onion and cook until the onion is melted down into a rich golden brown color, about 35 to 45 minutes. Stir frequently and turn the heat down or add a splash of water as necessary to prevent the onion from burning.
  • Add the salt, black pepper, garlic, and thyme and cook 1 minute more, stirring constantly. Cool.
  • Whisk together the eggs, cream, and corn starch slurry in a large bowl, and then whisk in the cooled caramelized onion. Whisk in the cheese.

To Assemble and Bake the Tartlets:

  • Preheat the oven to 375F.
  • Roll out the disk of dough on a lightly floured surface to a circle about 14 inches in diameter.
  • Use a 3-inch cookie cutter (or a glass with that diameter) to stamp out circles in the dough. Gather the scraps of dough, re-roll them, and continue stamping out circles until the dough is gone.
  • Press each dough circle into the well of a mini muffin tray. Fill each tart with 1 tablespoon of caramelized onion filling.
  • Bake until the crust is golden and the filling is set, about 25 to 30 minutes.
  • Let the tartlets cool until you can handle them, and then pop each one out of the mini muffin tray.
  • Serve warm or at room temperature.


  • This recipe makes 48 tartlets for a total of 12 servings. Each serving is 4 tartlets.
  • Store these tartlets wrapped in the fridge for up to 5 days.
  • To reheat these tartlets, place them on a baking tray and heat in a 375F oven until warm, about 8 minutes.


Serving: 4tartlets | Calories: 329kcal | Carbohydrates: 24g | Protein: 7g | Fat: 23g | Saturated Fat: 14g | Cholesterol: 90mg | Sodium: 291mg | Potassium: 91mg | Fiber: 1g | Sugar: 1g | Vitamin A: 741IU | Vitamin C: 2mg | Calcium: 117mg | Iron: 1mg