The Best Million Dollar Spaghetti

Preheat the oven to 350°F (175°C) and grease a 9×13-inch baking dish.
Cook the spaghetti: Boil water in a large pot and cook the spaghetti according to package instructions. Drain and set aside.
Prepare the beef mixture: In a large skillet, cook the ground beef over medium heat until browned, breaking it up with a spatula. Drain excess fat if necessary. Add the marinara sauce, Italian seasoning, garlic powder, onion powder, salt, and pepper. Simmer for 5-10 minutes, stirring occasionally.
Make the creamy layer: In a large bowl, mix together the softened cream cheese, sour cream, and melted butter until smooth and combined.
Assemble the spaghetti: Layer half of the cooked spaghetti in the prepared baking dish. Top with half of the creamy mixture, spreading evenly. Add half of the beef mixture on top, followed by a generous sprinkle of mozzarella and Parmesan cheeses.
Repeat the layers: Add the remaining spaghetti, the rest of the creamy mixture, the rest of the beef sauce, and top with the remaining mozzarella and Parmesan cheeses.
Bake: Cover the dish with aluminum foil and bake for 25 minutes. Then, remove the foil and bake for an additional 10-15 minutes, until the cheese is melted and bubbly.
Serve and enjoy: Let the Million Dollar Spaghetti sit for a few minutes before serving to allow it to set. Serve with a side of garlic bread or a salad for a complete meal.

Make-ahead: You can assemble this dish a day ahead and store it in the fridge. When ready to bake, let it come to room temperature and bake as directed.
Add veggies: For extra flavor and nutrition, feel free to add sautéed bell peppers, mushrooms, or spinach to the beef mixture.
Cheese variations: You can substitute the mozzarella for provolone, or even add ricotta to the creamy layer for an extra indulgent twist.
Ground beef alternatives: Ground turkey, chicken, or sausage can be used for a leaner or different flavor profile.