Preheat oven to 350 degrees F.

Make Meat Sauce: In a large skillet, cook and crumble the ground beef and Italian sausage, season with salt and pepper. Remove most of the grease. Add onions and garlic; cook until onion is translucent. Add all but ½ cup of marinara sauce to the mixture and stir to combine. Set aside.

Prepare noodles: Cook Spaghetti according to package instructions, just until 'al dente'. Drain, and place hot spaghetti in a large mixing bowl with butter and ½ cup reserved marinara sauce; toss to combine.

Make Cheese layer: Combine cream cheese, sour cream, and cottage cheese in a bowl and mix well.

Assemble: Pour HALF of the pasta into a 9x13'' pan. Smooth cheese layer on top. Top with remaining noodles. Add meat sauce on top and smooth into an even layer. Top with mozzarella cheese and parmesan cheese.

Bake for 30-40 minutes or until hot and bubbly. Check at 20 minutes; if cheese is browning too quickly, tent with tinfoil. Wait 15 minutes before cutting and serving.