Description

These Upside-Down Onion and Gruyere Tarts are a delightful combination of sweet caramelized onions, rich Gruyere cheese, and fragrant fresh thyme, all encased in flaky puff pastry. The tarts are baked until golden and then flipped to reveal a beautifully caramelized bottom topped with honey and herbs, making them an elegant appetizer or savory snack perfect for any occasion.

Ingredients

Scale

For the Tarts

1 sheet of puff pastry, thawed
1 yellow onion, thinly sliced
18 slices thinly sliced Gruyere cheese, or as needed
1 egg, beaten (for egg wash)

For the Topping and Flavoring

3 tablespoons honey or homemade hot honey, divided
Fresh thyme leaves, to taste
Salt, to taste
Black pepper, to taste

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Instructions

Preheat the Oven: Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper to prevent sticking and make cleanup easy.
Prepare Honey Base: Drizzle small amounts of hot honey onto the lined baking sheet, creating 9 separate honey spots that will flavor the base of each tart.
Cut Puff Pastry: Cut the thawed puff pastry sheet into 9 equal rectangles for individual tarts.
Assemble Tarts: Sprinkle fresh thyme leaves, salt, and black pepper over each honey spot. Press a slice of thinly sliced onion on top of each honey drizzle, followed by 1-2 slices of Gruyere cheese. Top each stack with a puff pastry rectangle, ensuring the edges are aligned.
Apply Egg Wash: Brush the top of each puff pastry rectangle with the beaten egg to promote golden browning during baking.
Bake the Tarts: Place the baking sheet in the preheated oven and bake for approximately 20 minutes, or until the puff pastry is puffed and golden brown.
Flip and Finish: Remove the tarts from the oven and carefully flip each tart over using a spatula so the honeyed onion and cheese base is on top.
Garnish and Serve: Drizzle additional hot honey over each tart and sprinkle with fresh thyme leaves. Allow to cool slightly before serving. Enjoy warm for the best flavor and texture.

Notes

You can substitute Gruyere with a similar melting cheese like Emmental or Comté if desired.
For a spicier kick, use homemade hot honey or add a pinch of chili flakes to the honey drizzle.
Make sure the puff pastry is fully thawed to ensure even baking and puffing.
These tarts are best served warm but can be reheated gently in the oven.
Use a sharp knife or pizza cutter to cut the puff pastry easily and cleanly.

Nutrition

Serving Size: 1 tart
Calories: 210
Sugar: 6g
Sodium: 180mg
Fat: 14g
Saturated Fat: 7g
Unsaturated Fat: 6g
Trans Fat: 0g
Carbohydrates: 16g
Fiber: 1g
Protein: 6g
Cholesterol: 55mg