Add 1 jar of the sauce to the cooked noodles. Set aside.
In a large skillet, brown ground beef and Italian sausage with onion and garlic. Drain grease and add the second jar of marinara sauce to the cooked meat. Set aside.
In a bowl, combine cottage cheese with cream cheese, sour cream, and half of mozzarella cheese. Set aside.
Add butter cubes to the bottom of a 13×9 deep dish casserole.
Spread half of the spaghetti (with sauce) in the bottom of the dish.
Top with ALL of the cheese mixture.
Follow up with the remaining half of the pasta (with sauce).
Add all the meat sauce to the top of the million dollar casserole.
Sprinkle the remaining mozzarella cheese on top, with the grated parmesan.
Bake casserole UNCOVERED in a 350 degree oven for 30-35 minutes.
Notes
If you prefer meatless, load up your sauce with green peppers, mushrooms, zucchini, spinach, and/or eggplant! Simmer the vegetables of your choice with your marinara sauce to cook them down and soften the texture.
Assemble baked spaghetti up to 24 hours in advance if desired. Keep covered in refrigerator and add an extra 15 minutes to baked time if chilled.
Freeze casserole by covering with foil and freezing for up to 30 days. Thaw in refrigerator for 24 hours before baking. I don’t recommend baking from frozen as it will dry out.
Swap out the cottage cheese for ricotta for a more classic flavor!