Preheat oven to 400 degrees F.

Place puff pastry on a parchment-lined baking sheet.

With a sharp knife, score the pastry along all sides, about 1/2-inch, to create a border.

Inside the border, poke the pastry all over with a fork.

In a large bowl, combine cherry tomatoes with Italian dressing and pepper.

Spread Dijon mustard evenly over the pastry.

Sprinkle with the Italian cheese blend, then top with the mozzarella cheese.

Arrange the tomato mixture evenly over the cheese.

Bake for 15 to 20 minutes, or until golden brown.

Let stand for 5 minutes before cutting into squares and serving.