Cover the bowl with plastic wrap and let the dough rest at room temperature for about 2 hours, until it has roughly doubled in size.
Lightly oil a 10-inch cast-iron skillet. Transfer the dough into the pan and use your hands to press it evenly, stretching it to cover the bottom and edges.
Spread the pizza sauce evenly over the dough. Sprinkle the mozzarella cheese on top and add pepperoni slices if using.