In a medium size mixing bowl, combine 3 cans crushed tomatoes and 2 teaspoons Italian seasoning.
In a separate mixing bowl, combine 8 oz ricotta cheese, 8 oz cream cheese, ½ cup sour cream, 1 cup shredded mozzarella cheese, and the remaining 1 teaspoon Italian seasoning.
Brown 1 pound ground sweet Italian sausage with 2 tablespoons minced garlic and ½ diced onion in a large skillet over medium heat. Drain off the excess grease.
Then stir in have the tomato sauce mixtures.
Cook 16 oz spaghetti noodles based on the package directions. Drain and return back to the pan. Mix with the remaining tomato sauce mixture.
Place half of the ½ cup butter slices on the bottom of a 9X13 pan. Top with half of the spaghetti mixture, then spread the cheese mixture on top.
Top the cheese mixture with the remaining spaghetti noodles and place the remaining butter slices on top of the second layer of noodles.
Pour the meat sauce mixture evenly over the top and top with the remaining 2 cups shredded mozzarella cheese.