Preheat oven to 350° F. Prepare a 9 X 13-inch baking dish by spraying it with cooking spray.
In a medium bowl combine the egg, ricotta and Parmesan cheeses, 1 cup of the mozzarella, Italian seasoning, and the parsley. Mix until well combined.
Set 30 whole pepperoni slices aside and cut the remainder up into quarters.
Compliments of 365 Days of Baking and More