Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.

Roll out the puff pastry to 1/4-inch thick and cut into tree shapes.

Spread a thin layer of pesto on each pastry shape.

Whisk the egg and water together and brush the mixture over the pastry shapes.

Sprinkle grated Parmesan cheese over each pesto-covered tree.

Bake for 15-20 minutes until golden brown.

Garnish with halved cherry tomatoes and chopped basil, then serve.