Grease a 9x13 inch baking dish with some of the remaining butter. Spread half of the cooked spaghetti in the bottom of the dish.
Spread the cream cheese mixture evenly over the spaghetti.
Layer the remaining spaghetti on top of the cream cheese mixture. Dot with the remaining butter.
Pour the meat sauce over the top spaghetti layer, spreading to cover.
Sprinkle the shredded mozzarella and cheddar cheese evenly over the top.