Set a large pot over moderate heat. Once hot, drizzle in the oil and add the sausage. Break up with a wooden spoon and cook until crispy and no longer pink. Add the pepperoni slices and cook until just beginning to crisp up. Use a slotted spoon to transfer to a plate and set aside.

Add the mushrooms and red onion to the same pot and cook until softened and browned. Stir in the bell peppers, black olives, oregano, basil, fennel, crushed red pepper flakes, and a pinch of salt and pepper. Cook until the bell peppers have softened, about 5 minutes.

Return the sausage and pepperoni to the pan and stir in the pizza sauce and cooked gnocchi. Give it all a big stir and then spread out evenly. Remove from the heat and sprinkle the mozzarella and parmesan over the top. Season with a tiny bit of dried oregano and/or crushed red pepper flakes. Pop under a preheated broiler until melted and golden brown on top. Serve with a salad and enjoy!