Drizzle the olive oil into a 9-inch to 12-inch cast iron skillet (or other heavy oven safe skillet.) Use a pastry brush to distribute the oil over the bottom and up the sides of the pan.

In a medium mixing bowl, stir together the pizza sauce, 1 cup of the mozzarella and the pepperoni slice quarters until evenly mixed. Drop in one piece of dough at a time, use tongs or two forks to turn it to coat both sides, then transfer to the prepared pan. Repeat with the remaining pieces of dough. If any of the sauce mixture remains in the bowl, use a spoon to dollop it in small amounts over the dough that is in the pan. Sprinkle the remaining cheese evenly over the prepared dough and let rise for 10 minutes before preheating your oven to 425°F with a rack positioned in the center third of the oven.

When the oven reaches the correct temperature, slide the pan into the oven (on top of a rimmed baking sheet to catch drips if the dough, cheese and sauce look precariously close to the top of the pan. Remember it will rise higher as it bakes!) Bake for 25-30 minutes (or longer, if necessary) or until the bread is puffy and well-set and the cheese is melted and browned. Remove the pan from the oven and let it rest for 10 minutes. Lay a platter or plate that's slightly larger over the top of the pan before carefully inverting.

If desired, you can sprinkle sliced green onions over the Bubble Pizza before serving. Serve warm!