Preheat the oven to 350 and bring a large pot of water to boil. Add a tbsp of salt and cook pasta for 6-7 minute, then strain. Pasta will be firm.
In a large skillet, brown the sausage or chorizo, about 5 to 10 minutes. Add the onion and mushrooms (plus any vegetables or pepperoni you’d like to add), cook for 3-4 minutes or until vegetables soften. Add in the cooked pasta and sauce. Mix well and remove from the heat.
Place half of the casserole mixture into an 8 x 8 casserole dish. Sprinkle 1 1/2 cups of shredded mozzarella cheese on top. Bake for 15 minutes and remove, then top with 1/2 cup of shredded mozzarella and 1/4 cup Parmesan cheese. Bake a few more minutes until cheese is melted and serve.