Preheat your oven to 400 degrees. Line a large baking sheet with parchment paper and set aside.

Unfold the thawed puff pastry onto a lightly floured surface. Use a sharp knife or pizza cutter to cut it into 12 even squares, roughly 3 by 3 inches each.

Arrange the squares on the prepared baking sheet, spacing them about half an inch apart. Using the tip of a knife, score a shallow border about a quarter inch in from each edge of every square. Do not cut all the way through. This border lets the outer edges puff higher than the center.

Spoon a small amount of pizza sauce inside the scored border of each square, about one teaspoon per square. Spread it gently with the back of the spoon, staying inside the scored line.

Scatter shredded mozzarella over the sauce on each square, then lay 2 to 3 mini pepperoni or 1 regular slice on top. Sprinkle Italian seasoning over all the squares. Lightly brush the exposed border edges with olive oil.

Bake for 14 to 16 minutes, until the pastry is deep golden brown at the edges and the cheese is melted and just starting to bubble. Check at 13 minutes since ovens vary.

Let the squares cool on the pan for 2 minutes before transferring to a serving board. Sprinkle with red pepper flakes if you like heat and serve warm.