Spaghetti Casserole - cooking recipe

Ingredients

1 box spaghetti dinner with herb sauce mix included (I prefer Kraft Tangy Italian)
2 c. shredded Mozzarella cheese
1 c. shredded medium Cheddar cheese
1 lb. ground beef
1/4 c. chopped onion (optional)
1 small can chopped mushrooms, drained (optional)
1 (6 oz.) can tomato paste
2 (6 oz. each) cans water
1 Tbsp. margarine

Preparation

Prepare spaghetti as directed.
While spaghetti is cooking, brown ground beef and onion; add the herb sauce mix, tomato paste, water, margarine and mushrooms.
Bring to a boil; reduce heat. Simmer 10 minutes, stirring occasionally.
Drain spaghetti.
Mix 2 cheeses together.