Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking dish with non-stick spray.
Cook spaghetti according to package instructions. Drain and toss with melted butter.
In a large skillet, cook ground beef over medium heat until browned. Drain excess fat, then stir in marinara sauce. Simmer for 5 minutes.
In a medium bowl, mix cream cheese, ricotta, sour cream, garlic powder, and a pinch of salt and pepper until smooth.
Layer half of the spaghetti in the prepared baking dish. Spread the cheese mixture evenly on top, followed by the remaining spaghetti.
Pour the meat sauce over the top and spread evenly. Sprinkle mozzarella and Parmesan cheese over the casserole.
Bake for 25-30 minutes or until bubbly and the cheese is melted. Garnish with fresh parsley before serving.
