1 lb. box ziti
1 jar spaghetti sauce
1 15 oz container of ricotta cheese
1 cup mozzarella cheese
Parmasean cheese
ground beef or sausage, if desired

Cook ziti according to package directions. While that is cooking, in a casserole dish combine ricotta cheese, mozzarella cheese, and about a half cup parmasean cheese. If you decide to add meat to the dish, I brown the meat and add the spaghetti sauce to it when it is browned and heat the sauce. I find that this speeds up the baking process. Add the spaghetti sauce to the cheese mixture.
When the ziti is cooked, drain and add to sauce/cheese mixture. I usually do this in increments, makes it a bit easier. (I will also add extra spaghetti sauce if I think it needs it.)
If desired, add more mozzarella and parmasean cheese on top before baking. Bake 15-20 minutes in a 375 degree oven.
Before:

After:
