Cook the pasta per the directions on the package for 'al dente'. Drain, then return to the pot. Set aside.
4 oz rotini pasta, 4 oz medium shell pasta, 4 oz corkscrew pasta, 4 oz wagon wheel pasta
While the pasta cooks add the oil to a large skillet set over medium/high heat. Once the oil's hot add the peppers and onions, sauteeing and stirring often, until softened.
1 tbsp extra virgin olive oil, 1 cup diced green bell pepper, 1 large yellow onion
Add the sausage to the skillet cooking and crumbling until completely cooked through. Strain of grease. Transfer the meat mixture to the pot with the cooked and drained pasta.
1 lb ground Italian sausage
Add the pepperoni, Parmesan cheese, 1/2 cup of mozzarella cheese, and all of the sauce to the pot. Stir everything together until evenly combined.
3 oz pepperoni slices, 1 1/2 cups shredded Parmesan cheese, 2 cups shredded mozzarella cheese, 2 24 oz jars marinara sauce
Lightly spray a 9x13" baking dish with nonstick spray. Transfer the pasta mixture to the dish, then spread it out in an even layer. Sprinkle the remaining shredded cheese evenly out overtop.
Tightly cover the dish with aluminum foil then bake at 350° for 30 minutes. Carefully remove the foil then bake for another 10 minutes.
Remove the dish from the oven and let the pasta rest for 5-10 minutes.
Serve warm & enjoy!