Remove sausage from casing and add to large skillet.
Cook over medium heat, crumble sausage and cook until no longer pink.
Drain grease, reserving 2 tablespoons. Set sausage aside.
Add reserved grease to pan, add chopped onions and garlic, sauté until translucent.
Pour diced tomatoes into skillet with onions and garlic.
Sprinkle oregano and basil, salt and pepper into the tomato mixture. Cook for 5 minutes over medium heat.
Add sausage back to skillet and bring to a boil.
Cover, reduce heat and simmer for 30 minutes, stirring occasionally.
Cook pasta, in a large pot, according to package directions.
Drain, rinse with hot water and add back to large pot.
Mix sausage and tomato mixture into pot with pasta, stir.
Add shredded mozzarella cheese to pot and mix until combined.
Serve with salad, garlic bread, or just by itself.