Preheat oven to 375 degrees. Lightly spray a 16-inch pizza pan with cooking spray. Set aside.
In a medium-size skillet, heat a light drizzle of olive oil. Add the sausage, onion, green bell pepper, and mushrooms. Season with the Italian seasoning, garlic salt, and red pepper flakes. Cook for 10 minutes, or until no pink remains in sausage. Remove from the heat and drain or spread onto double-lined paper towels to remove excess oil.
Stretch the pizza crust into a roughly 12x16-inch rectangle. Spread with 1/2 cup of the pizza sauce and sprinkle with 1 cup of the mozzarella cheese. Sprinkle the crumbled sausage mixture over the cheese, arranging the black olive and mini pepperoni slices on top. Cover with 1 cup of mozzarella cheese.
Begin to roll, starting with the widest edge. Use a sharp knife to carefully cut into 16 equal portions.When cutting into portions, if the rolls come apart slightly, don't panic; rewrap and press together. Place side by side on the prepared pan, starting in the center of the pan and forming into a circle.. As the cheese melts and the dough bakes, the filling will adhere.
Bake for 20 minutes, or until golden. Sprinkle with the Parmesan cheese and the remaining cup of mozzarella cheese. Continue to bake for another 5 minutes, or until the cheese melts.
Sprinkle with additional grated Parmesan cheese before serving, if desired, and serve with the remaining cup of warm pizza sauce on the side, for dipping.