Prepare the Puff Pastry

1. Preheat Oven: Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper.
2. Roll Out the Pastry: Roll out the puff pastry sheet on a lightly floured surface. If using store-bought, make sure to unroll it gently.
3. Cut the Shape: Using a sharp knife, cut the pastry into a large triangle shape to create the base of the tree. Then, cut smaller triangles from the remaining pastry to form the branches.

Assemble the Christmas Trees

4. Apply the Pesto: Spread a thin layer of pesto over the large triangle, leaving a small border around the edges.
5. Layer and Shape: Place the smaller triangle pieces on top of the large one, layering them slightly to mimic the shape of a Christmas tree. Make sure to overlap them slightly to create the tree effect.
6. Cut the Tree Shape: Using a sharp knife, cut the layered pastry into a Christmas tree shape, trimming the edges if needed.
7. Create the Tree Trunk: Use the leftover pastry to cut small rectangles for the trunk of the tree, placing one at the bottom of each tree.

Bake the Christmas Trees

8. Brush with Egg Wash: Beat the egg and brush it over the pastry to give the trees a golden, shiny finish once baked.
9. Add Garnishes: Sprinkle Parmesan cheese and pine nuts (if using) over the trees.
10. Bake: Place the trees on the prepared baking sheet and bake for 10-12 minutes, or until golden brown and puffed.

Serve the Trees

11. Cool Slightly: Let the trees cool for a few minutes before serving.
12. Garnish and Serve: Serve warm, garnished with fresh basil leaves or extra grated Parmesan, if desired.