Bring to a boil 4 L of water and 2 tbsp of salt. Add pasta, stir and bring water to a boil again. Allow to boil 8 - 11 minutes or to taste. Preheat oven to 325. While the pasta is cooking, spray a large baking dish with Pam or alternative. I use the lasagna size dish. Dice up the onion and add to the dish. Drain the cans of Mushrooms (fresh mushroom may also be used in place of the canned) and add to the dish with the onions. Dice the cheese in approximately 1/2 inch size cubes and set aside. By this time, the pasta should be cooked. Drain the pasta and add to the dish. Using a large spoon, mix the pasta sauce into the pasta, onions and mushrooms. When mixed, add the cubed cheese and mix into the pasta mixture. Top with a piece of foil and seal the edges. Bake for 30 minutes. Remove foil and bake for another 5 minutes. Serve with garlic bread or a salad of your choice.