1-First, preheat your oven to 350°F (175°C) as outlined in the directions. This sets the stage for even baking. Then, in a large skillet, cook and crumble the ground beef and sausage over medium heat, seasoning with salt and pepper. Once browned, drain most of the grease, add the chopped onion and minced garlic, and cook until the onion is translucent. Stir in all but 1/2 cup of the marinara sauce and set aside.

2-Next, cook the spaghetti noodles according to package directions until al dente, then drain well. Toss the cooked noodles with the butter and the reserved 1/2 cup marinara sauce to keep them flavorful and moist.

3-In a separate bowl, mix together the softened cream cheese, sour cream, and cottage cheese or ricotta cheese until well combined to create the cheese layer. Now, assemble the casserole in a 9×13 inch baking pan: spread half of the noodle mixture evenly in the bottom, add the entire cheese layer, top with the remaining noodle mixture, and finally spread the meat sauce evenly over the top.

4-Sprinkle the shredded mozzarella cheese and grated Parmesan cheese evenly over the top, then bake uncovered for 30 to 40 minutes, or until the cheese is bubbly and the edges turn golden brown. If the cheese starts to brown too quickly, cover loosely with aluminum foil and let the casserole rest for 15 minutes before serving.