Remove sausage from casing and add to a 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 the 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 the skillet and bring to a boil.
Cover, reduce heat and simmer for 30 minutes, stirring occasionally.
In a large pot over medium high heat, bring water to a boil and cook pasta to al dente. Drain and add back pot.
Add sausage and tomato mixture into pot with pasta, stir.
Add shredded mozzarella cheese and stir until combined.
Serve with side salad, garlic bread, or just by itself.