1. Preheat oven to 400°F. Line with parchment paper.
2. Roll puff pastry out and cut into 9 rectangles. Top each with a spoonful of pesto, followed by a tomato slice and finishing with fresh mozzarella.
3. Fold 2 opposite corners and pinch together create a "bundle". Once completed, put in refrigerator for 15-30 minutes to allow pastry to set. During this time, create an egg wash with 1 egg white and a splash of water whisked together.
4. Remove from refrigerator and brush the exposed pastry with egg wash. Sprinkle with optional seasoning. Bake 20-25 minutes. Cool for 5 minutes, drizzle with balsamic glaze and enjoy!