Calzone, literally “pant leg,” is a pizza folded onto itself—a closed envelope of dough with the toppings on the inside. It makes sense to cut the ingredients for the fillings into relatively small pieces, since this makes the calzone easier to eat.
Prepare through the first rise:
      Basic Pizza Dough or Bread Machine Pizza Dough
Preheat the oven to 450°F. Lightly grease a baking sheet. Divide the dough in half and form each half into a ball. Place on a lightly floured work surface, sprinkle with flour, and cover with a dish towel or plastic wrap. Let stand for 20 minutes. Meanwhile, heat in a skillet over medium-high heat:
      2 teaspoons olive oil
Add and sauté until softened, about 5 minutes:
      1 red bell pepper, thinly sliced
      1 green bell pepper, thinly sliced
      1 onion, thinly sliced
Coarsely chop and combine with:
      8 ounces pepperoni, thinly sliced
      Salt and ground black pepper to taste
Shape each ball of dough into a thick disk and let stand for about 5 minutes. Roll each one into a 10-inch round. Divide the filling among the rounds. Fold the dough over, making a half circle, and tightly seal the edges with your fingertips. Reduce the oven temperature to 400°F. Place the calzones on the baking sheet and bake until nicely browned, 30 to 35 minutes. Serve hot or at room temperature.