Preheat the oven to 400°F. Line a baking sheet with parchment paper.
Cut the tomatoes in half and the basil into strips.
Unroll the pastry sheets and cut each into 9 equal squares. Arrange them on a prepared baking sheet.
Use a butter knife to score a smaller square just away from the edge of each cut square. Use a fork to prick the smaller square a few times.
Whisk the egg and water in a small bowl, and use a pastry brush to lightly cover each square in the egg wash.
Add the tomatoes to a medium bowl, along with the olive oil and salt/pepper to taste. Toss to coat.
Sprinkle mozzarella cheese in the center of each pastry square, then sprinkle with Italian seasoning, and top with 3-4 tomato halves, cut side up.
Transfer the baking sheet to the oven, and bake for 13-15 minutes, until golden brown.
Remove from the oven and top with a few strips of shredded basil to serve.