Ingredients
Scale
- 1 sheet of puff pastry (thawed if frozen)
- 3 large onions (thinly sliced)
- 1 cup Gruyere cheese (grated)
- 2 tablespoons olive oil
- 1 tablespoon balsamic vinegar
- 2 teaspoons fresh thyme (or 1 teaspoon dried thyme)
- Salt and pepper to taste
- 1 egg (beaten, for egg wash)
Instructions
- Preheat your oven to 400°F (200°C).
- Caramelize the onions in olive oil for 15 minutes, then add balsamic vinegar and thyme, cooking for 5 more minutes.
- Roll out the puff pastry on a baking sheet, leaving a border.
- Spread the caramelized onions over the pastry and sprinkle with Gruyere cheese.
- Brush the edges with beaten egg and bake for 25-30 minutes until golden.
- Cool for 30 minutes, then slice and serve.
Notes
- Feel free to add more cheese if desired.
- This tart can be served warm or at room temperature.
- Prep Time: 15 minutes
- Cook Time: 40 minutes
- Category: Appetizer
- Method: Baking
- Cuisine: French
- Diet: Vegetarian