1Slice Italian sausage into bite size pieces while slightly frozen. Place in large pot with 4 to 5 tablespoons of olive oil, garlic, oregano and the butter. I personally like a lot of garlic and oregano and that part is personal preference. Slice the red and green peppers into long slices after cleaning the seeds out. Place these into the pot with the sausages. Add the entire package of fresh sliced mushrooms and the chopped onion. Stir frequently while cooking on medium heat. In the mean time cook the penne pasta until almost done. Remove from heat and drain (do not rinse)(set aside). Once the sausage mixture is done (cooked about a 1/2 hour or so)(do NOT drain juices from pot) add the stewed tomatoes to the sausage mixture. I pour the tomatoes into a bowl and squish them up so that there are no whole pieces. Add as much parmesan cheese as you would like and the pasta to the sausage mixture. Cook for about 15 to 20 minutes on low heat stirring frequently. Turn the burner off and add the 8 oz of mozzarella cheese to the pot and stir until the cheese is melted.