Preheat oven to 350°F.
Cook pasta el dente according to package directions. Drain well.
Meanwhile, brown onion, sausage, and beef in a large skillet over medium heat. Drain any fat.
Add in garlic and red and green peppers, and cook 2-3 minutes until tender. Add drained tomatoes, oregano, and pasta sauce. Stir well.
Combine pasta and tomato sauce and pour into a greased 9×13 pan. Top with cheese and pepperoni slices.
Bake 35-40 minutes uncovered or until cheese is melted and pasta is heated through.
