Step 1

If the pizza dough is cool, let it sit out at room temperature for at least 30 minutes before using.

Step 2

Preheat the oven to 450°F and set an oven rack in the lowest position. Drizzle a rimmed baking sheet with the olive oil.

Step 3

In a medium bowl, stir together the mozzarella, ricotta, Pecorino Romano (or Parmigiano Reggiano), salt, pepper, oregano, and red pepper flakes (if using).

Step 4

Divide the dough into two even balls. On a lightly floured work surface, roll each dough ball into a circle between 7 and 8 inches in diameter and ⅛ and ¼-inch thick.

Step 5

Spread 1 tablespoon of sauce over one half of each round of dough, leaving a 1-inch border. Top with the pepperoni slices and cheese mixture. (Just evenly spoon the cheese mixture on top of the sauce and pepperoni; no need to spread it.) Using your finger, dab a bit of water around the edges (this will help the dough seal). Holding the filling in place with one hand, use your other hand to fold the bare half of the dough over the filling to form a half-moon shape. Using a fork, press the edges of the dough together to seal. Roll the edge up to seal again.

Step 6

Transfer the calzones to the greased baking sheet. Brush with the egg wash and then prick each calzone with a fork 5 times to allow steam to escape during baking. Bake for 22 to 25 minutes, until puffed and golden brown. Let cool for about 15 minutes, then serve.