Make Meat Sauce: In a large skillet cook and crumble the ground beef and Italian sausage and season with salt and pepper. Remove most of the grease. Add onions and garlic and cook for a few minutes until onion is translucent. Add all but 1/2 cup of the marinara sauce (reserve 1/2 cup for later) 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 1/2 cup reserved marinara sauce and toss to combine.
Make Cheese layer: Combine cream cheese, sour cream and cottage cheese in a bowl and mix well. Smooth over noodles in the pan.
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 it around 20 minutes and if the cheese is browning too quickly, tent a piece of tinfoil over it. Wait at least 15 minutes before cutting and serving, to allow it to set up. Enjoy!
To Make Ahead: You can prepare this spaghetti casserole 1 day ahead of time. Follow recipe instructions up to step 8 (just before baking). allow it to cool, cover it well with plastic wrap and store it in the refrigerator until ready to bake. Or, prep the sauce, noodles and cheese layer 1-3 days ahead of time and assemble right before baking.To Freeze: Prepare recipe right up until the baking step. Cover well with greased aluminum foil and freeze for up to 3 months. When ready to eat, thaw in the refrigerator for 1 to 2 days, then bake for about 20 minutes, covered, and then 20-25 minutes uncovered. If baking from frozen, bake covered for about 40 minutes, then uncover and bake at least 30-40 minutes longer, or until bubbly and warm.Vegetarian Million Dollar Spaghetti: leave out the meat entirely or substitute plant based meat!Ground Beef vs. Sausage: I like to use both ground beef and ground Italian sausage in this recipe but you don't have to use both. If you do, consider saving the leftover 1/2 pound of Italian sausage to make Baked Ziti or Pizza Casserole.Pasta: we use spaghetti for million dollar spaghetti but feel free to use your favorite kind of pasta.