Preheat your oven to 425°F.

Mix the filling in a bowl by combining diced cooked ham, shredded mozzarella, ricotta, and Parmesan cheeses. Sprinkle in dried oregano and garlic powder, then stir until everything is well-blended.

Divide the pizza dough into four equal portions. Roll each piece into a circle approximately 8 inches in diameter.

Spoon a quarter of the filling onto one half of each dough circle, leaving about a ½-inch border around the edge. Brush the edges with the beaten egg.

Fold the dough over the filling to create a half-moon shape. Use a fork to crimp and seal the edges tightly.

Transfer the assembled calzones to a parchment-lined baking sheet. Brush the tops with olive oil and cut a small slit in each one.

Bake for 15-20 minutes, or until they are golden brown and puffed up. Let them cool for about 5 minutes before serving.