01 - Preheat oven to 350°F. Grease a 9x13-inch baking dish with cooking spray or butter.
02 - Cut the refrigerated biscuit dough into 1-inch pieces. Place the pieces in the prepared baking dish, spreading them evenly across the bottom.
03 - In a medium bowl, combine the biscuit pieces with 1 cup of pizza sauce and half of the shredded mozzarella cheese. Toss gently until all pieces are evenly coated.
04 - Spread the coated biscuit pieces evenly in the greased baking dish. Pour the remaining 1/2 cup of pizza sauce over the top.
05 - Layer the sliced pepperoni, black olives, and diced bell peppers over the biscuit base. Sprinkle the remaining mozzarella and cheddar cheese evenly over all toppings.
06 - Evenly sprinkle the dried Italian herbs, garlic powder, crushed red pepper flakes (if using), salt, and black pepper over the entire casserole.
07 - Bake uncovered for 30 to 35 minutes until the biscuits are puffed and golden brown, and the cheese is melted and bubbly throughout.
08 - Remove from the oven and let the casserole rest for 5 minutes before serving. This allows the cheese to set slightly for easier scooping.