Ingredients
For the Caramelized Onions:
- 2 large onions, thinly sliced
- 1 ½ tablespoons butter
- 1 tablespoon olive oil
- ½ teaspoon kosher salt
- ½ teaspoon sugar
- 1 teaspoon fresh thyme leaves, plus more for serving
- 1 tablespoon water, or more as needed
For the Christmas Tree:
- 2 sheets puff pastry, thawed but kept cold
- 4 tablespoons basil pesto
- Caramelized onions, cooled (from above)
- 1 ¼ cups shredded mozzarella cheese
- 1 egg (for egg wash)
- ¼ cup grated Parmesan cheese, for topping
Instructions
- Prepare Caramelized Onions: In a large skillet over medium heat, melt the butter with olive oil. Add the thinly sliced onions, kosher salt, sugar, and fresh thyme leaves. Stir to combine and cook gently, stirring occasionally, until the onions are soft, deeply golden, and caramelized, about 25-35 minutes. Add water as needed to prevent sticking. Remove from heat and let cool completely.
- Preheat Oven and Prepare Puff Pastry: Preheat your oven to 400°F (200°C). Roll out one puff pastry sheet on a lightly floured surface to soften the folds. Place it on a baking sheet lined with parchment paper.
- Assemble the Christmas Tree Layers: Spread 2 tablespoons of basil pesto evenly over the first puff pastry sheet. Evenly spread half of the cooled caramelized onions on top, followed by half of the shredded mozzarella cheese.
- Second Puff Pastry Layer: Place the second puff pastry sheet over the first, gently pressing down. Spread the remaining 2 tablespoons of basil pesto over the second sheet, then add the rest of the caramelized onions and mozzarella cheese evenly.
- Cut the Christmas Tree Shape: Using a sharp knife, cut the layered puff pastry into a large triangle shape resembling a Christmas tree. Remove the excess dough from around the shape.
- Create Branches: Starting from the base of the triangle, make evenly spaced cuts on each side towards the center, creating ‘branches.’ Twist each branch gently away from the center to expose the layers.
- Apply Egg Wash and Add Toppings: Beat the egg and brush it over the entire tree to give it a golden sheen once baked. Sprinkle grated Parmesan cheese evenly over the top. Add additional fresh thyme leaves if desired for garnish.
- Bake: Bake in the preheated oven for 20-25 minutes or until the puff pastry is puffed, golden, and cooked through, and the cheese is melted and bubbly.
- Serve: Allow the Christmas Tree Appetizer to cool slightly before serving. Garnish with extra fresh thyme leaves and cut into slices to serve as a festive appetizer.
Notes
- Make sure to keep the puff pastry cold before baking to help it puff properly.
- Caramelizing the onions slowly is key to developing the rich flavor of this appetizer.
- You can substitute mozzarella with a mix of mozzarella and Gruyère for extra depth of flavor.
- This appetizer can be made ahead: assemble and refrigerate before baking, then bake just before serving.
- For a vegan version, use vegan puff pastry and cheese alternatives.
- Prep Time: 40 minutes
- Cook Time: 30 minutes
- Category: Appetizer
- Method: Baking
- Cuisine: Italian-inspired
- Diet: Vegetarian
