Preheat the oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish.

Cook the pasta: Boil the spiral pasta according to package directions until al dente. Drain and set aside.

Prepare the beef mixture:

In a large skillet over medium heat, cook the ground beef and diced onion until the beef is browned and the onion is soft. Drain excess fat.

Add the sautéed mushrooms, tomato sauce, pizza sauce, and tomato paste. Stir to combine.

Mix in sugar, onion powder, garlic powder, and dried oregano. Simmer for 5-10 minutes, stirring occasionally.

Assemble the casserole:

In a large mixing bowl, combine the cooked pasta and beef mixture, stirring until well coated.

Pour half of the mixture into the prepared baking dish. Sprinkle with 2 cups of mozzarella cheese.

Layer with pepperoni slices.

Add the remaining pasta and meat mixture. Top with the remaining mozzarella cheese and sprinkle the Parmesan cheese evenly.

Bake:

Cover with aluminum foil and bake for 20 minutes.

Remove the foil and bake for an additional 10-15 minutes, or until the cheese is melted and bubbly.

Serve: Allow the casserole to rest for 5 minutes before serving. Enjoy your cheesy, hearty pizza casserole!

Optional Additions: Try adding bell peppers, olives, or sausage for extra flavor and variety!