This recipe actually comes from the Kraft Foods website but it's a favorite at our house so I thought I'd share here.
8 oz. spaghetti
1/2 lb. Italian Sausage (casing removed, crumbled)
1 jar (14 oz) spaghetti saucse (1-3/4 cups)
1 egg, lightly beaten
1-1/2 cups shredded mozzarella cheese, divided
1/4 cup grated parmesan cheese
Preheat oven to 375 degrees. Spray 8 inch square baking dish with cooking spray; set aside. Cook spaghetti as directed on package. Meanwhile, brown sausage in medium skillet on medium heat; drain. Stir in sauce. Reduce heat to low and simmer 5 minutes, stirring ocassionally.
Drain spaghetti; place in a large bowl. Add egg and 1 cup of the mozzarella cheese and the parmesan cheese; toss to coat. Place in prepared baking dish; top with sausage mixture. Sprinkle with remaining 1 cup mozzarella cheese.
Bake 15 minutes or until heated through. Let stand 5 minutes before cutting to serve.