Spray a well-seasoned 12-inch cast iron skillet with cooking spray or wipe it down with a little oil.
Cover the entire bottom of the skillet with a deep layer of pepperoni. Don't leave gaps, this layer becomes the top of your pizza.
Sprinkle a layer of mozzarella over the pepperoni and season with Italian seasoning.
Spread the cooked sausage evenly over the mozzarella, then spoon the marinara directly over the sausage. Keep the sauce off the edges so it doesn't touch the dough.
Add the sliced cheese, then finish with the additional mozzarella.
Open the pizza dough and stretch it over the entire skillet. Press and tuck the excess dough down around the edges of the pan to build a thick crust.
Lightly brush the top of the dough with olive oil and sprinkle with more Italian seasoning.
Bake in a 400°F oven or grill for approximately 20 to 25 minutes, until the crust is golden brown and cooked through.
Using high heat gloves, carefully remove the skillet. Place a large plate or platter over the skillet, hold it firmly against the pan, and flip the whole thing over in one smooth motion.
Slowly lift the skillet away. The pizza should release easily thanks to the rendered pepperoni fat. Slice and serve.
