Gather the ingredients.
Heat the oven to 350 F. Lightly grease a 9x13 baking pan.
Cook the pasta in boiling salted water following package directions. Drain well and set aside.
While the pasta is cooking, heat the olive oil in a large sauté pan or skillet over medium heat. Add the mushrooms and sauté until golden brown. Remove to a plate and set aside.
Add the ground beef and onion to the skillet and cook, stirring, until the onion is translucent.
Add the bell pepper and garlic and continue cooking, stirring, until the beef is no longer pink. If necessary, drain and discard excess grease.
Add the basil, oregano, crushed red pepper, pizza sauce, and tomatoes, along with the olives, pepperoni, and the reserved cooked sliced mushrooms. Heat until the sauce begins to simmer. Taste and add salt and freshly ground black pepper, as needed.
Combine the beef and pepperoni sauce mixture with the drained pasta. Toss to blend thoroughly.
Spoon half of the pasta mixture into the prepared baking dish. Top with half of the shredded cheese.
Spoon the remaining pasta mixture over the cheese layer and finish with the remaining cheese.
Bake for 25 to 35 minutes, until hot and bubbly and the cheese is thoroughly melted.