Preheat oven to 375 degrees F.
Melt the butter in a small cast iron skillet and cook the mushrooms until tender.
Add in 1 Tbsp of pizza sauce followed by 1/2 of the shredded mozzarella.
Add on some pepperoni and banana peppers (or whatever toppings you like best.)
Repeat these layers twice more ending with the Pecorino Romano cheese on top.
Bake for 10-15 minutes.