Description
A cozy, elegant tart featuring sweet, jammy caramelized onions beneath a creamy custard filling, all in a flaky crust.
Ingredients
Scale
- 1 pie crust
- 4 large onions, thinly sliced
- 2 tablespoons olive oil
- 2 tablespoons butter
- 1 teaspoon salt
- 1 teaspoon sugar
- 1 tablespoon balsamic vinegar
- 1 cup grated cheese (such as Gruyère or Swiss)
- 2 eggs
- 1 cup heavy cream
- Fresh thyme (optional, for garnish)
Instructions
- Preheat the oven to 375°F (190°C).
- Heat the olive oil and butter together in a large skillet over medium heat until the butter foams; add the thinly sliced onions, sprinkle in the salt and sugar, and stir to coat.
- Cook the onions, stirring frequently, until they’re deeply caramelized and jammy — this will take about 20–25 minutes. Stir in the balsamic vinegar and remove from heat.
- Roll out the pie crust and place it into a tart pan, pricking the bottom lightly to prevent bubbles.
- Spread the caramelized onions evenly over the crust, then sprinkle the grated cheese on top.
- In a bowl, whisk together the eggs and heavy cream until smooth, then pour this mixture over the onions and cheese.
- Bake the tart for 30–35 minutes, until the filling is set and golden brown. Let it cool for 10–15 minutes before slicing.
- Garnish with fresh thyme if desired and serve warm.
Notes
Allow the tart to cool before storing; it keeps well for up to 4 days in the refrigerator.
- Prep Time: 15 minutes
- Cook Time: 35 minutes
- Category: Appetizer
- Method: Baking
- Cuisine: French
Nutrition
- Serving Size: 1 slice
- Calories: 350
- Sugar: 5g
- Sodium: 400mg
- Fat: 25g
- Saturated Fat: 12g
- Unsaturated Fat: 10g
- Trans Fat: 0g
- Carbohydrates: 38g
- Fiber: 2g
- Protein: 8g
- Cholesterol: 80mg