This upside down deep dish pizza recipe comes together in one pan. Cook the onions and green bell peppers, then assemble the pizza in the same pan – just cover with dough and put in the oven for 20 minutes. Be extremely careful and be sure to wear oven mitts when flipping the pizza out of the pan.
Heat 1 tablespoon of olive oil in a 12-inch (30 cm) cast-iron skillet over medium-high heat. Once the pan is hot, add the onion and cook until softened, about 4 minutes. Remove from the pan and set aside.
Add the green pepper and cook until softened, about 5 minutes. Remove from the pan and set aside.
Turn off the heat. Grease the pan with nonstick spray.
Arrange the pepperoni in an even layer on the bottom of the pan. Top with the green peppers, onions, Parmesan, and mozzarella. Arrange the provolone slices over the shredded cheese in an even layer. Top with the pizza sauce and spread evenly.
On a lightly floured surface, roll out the pizza dough to a 12-inch (30 cm) round. Gently lay the pizza dough over the pizza sauce, making sure the dough reaches to the edges all around. Brush the dough with the remaining tablespoon of olive oil.
Bake for 25 minutes, until the dough is golden brown.
Carefully remove the skillet from the oven. Place a large baking sheet on top, then quickly invert the pizza onto the pan.
Return to the oven and bake for another 20 minutes, until the pepperoni begins to crisp.