Description
This tart features rich, buttery caramelized onions and sharp Gruyère cheese on flaky puff pastry, perfect for brunch or a cozy dinner.
Ingredients
Scale
- 1 sheet puff pastry, thawed
- 2 large onions, thinly sliced
- 2 tablespoons butter
- 1 tablespoon olive oil
- ½ teaspoon salt
- ¼ teaspoon black pepper
- 1 teaspoon fresh thyme (or ½ teaspoon dried)
- 1 tablespoon balsamic vinegar (optional, for depth)
- 1 cup shredded Gruyère cheese
- 1 egg (for egg wash)
Instructions
- Preheat oven to 400°F (200°C).
- Heat butter and olive oil in a skillet over medium heat.
- Add onions, salt, pepper, and thyme. Cook slowly for 20–25 minutes, stirring often, until onions are golden and caramelized.
- Add balsamic vinegar and cook 1 minute more.
- On a baking sheet, unfold the puff pastry and score a 1-inch border around the edges with a knife (don’t cut through). Brush edges lightly with beaten egg.
- Spread caramelized onions evenly inside the border and sprinkle Gruyère on top.
- Bake for 20–25 minutes until pastry is puffed and golden and cheese is melted.
- Slice and serve warm.
Notes
Cook onions low and slow for the sweetest flavor. Add a handful of cooked mushrooms for an extra savory twist. Use Gruyère for best melt and flavor, but Swiss cheese also works.
- Prep Time: 10 minutes
- Cook Time: 35 minutes
- Category: Appetizer
- Method: Baking
- Cuisine: French
Nutrition
- Serving Size: 1 slice
- Calories: 310
- Sugar: 4g
- Sodium: 450mg
- Fat: 20g
- Saturated Fat: 10g
- Unsaturated Fat: 8g
- Trans Fat: 0g
- Carbohydrates: 30g
- Fiber: 1g
- Protein: 8g
- Cholesterol: 45mg