Preheat the oven: Preheat the oven to 400°F and line a baking sheet with parchment paper.
Prepare the filling: In a bowl, combine mozzarella, cheddar, bell peppers, carrots, spinach, red onion, garlic, Italian seasoning, salt, and pepper.
Roll out the pastry: Roll out the puff pastry on a lightly floured surface into a rectangle.
Add the filling: Spread the vegetable and cheese mixture evenly over the pastry, leaving a small border.
Roll and slice: Roll the pastry tightly, slice into rounds, and place on the baking sheet.
Brush with egg wash: Brush the tops with beaten egg.
Bake: Bake for 18-22 minutes until golden brown and cheese is melted.
Serve: Let cool slightly before serving.