1. Arrange a rack in the middle of the oven and heat to 375°F. Coat a 12-cup muffin tin with cooking spray.
2. Divide pizza dough into 12 equal portions (about 1 1/4 ounces each). Working with one piece of dough at a time, roll into a ball, then use your fingers to flatten and stretch into a 3- to 4-inch round. Repeat with remaining pieces of dough.
3. Place 1/2 teaspoon of the marinara sauce in the center of each dough round (no need to spread the sauce), then top each with a piece of mozzarella cheese and 2 slices of pepperoni. Fold the edges of the dough up and round the filling, then pinch them together, forming a small bundle.
4. Stir the butter, garlic, and salt together in a small bowl. Dip the pizza bombs, one at a time, into the butter mixture, and turn to coat. Place seam-side down into each muffin well. Sprinkle the top of each pizza bomb with 1/4 teaspoon Parmesan cheese and a pinch of Italian seasoning.
5. Bake until golden-brown, 15 to 20 minutes. Remove from the pan and cool for 5 minutes or until cool enough to handle. Serve with warm marinara sauce.
