The first time I made this for my family it became an instant favorite. It tastes so good that my Daughter-in-Law who lives in California called me the other day because she wants to prepare it for a get together at work and needed my recipe. I have to admit that it was inspired by a dish I tried at Olive Garden and I would have to say that it is pretty darn close.
Slice 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.
This can be baked with additional mozzarella cheese on the top - but it is juicier straight out of the pot. If you choose to bake it, cover the entire top with mozzarella cheese and bake until browned. My family also likes cheesy garlic bread served with this dish. Enjoy!