Preheat the oven to 350°F. Spray a large baking dish with cooking spray, and set aside.
Bring a large pot of salted water to a boil. Cook the pasta according to the package directions. Drain and set aside.
In a large skillet over medium heat, add the ground beef, onion, pepper, and spices. Cook, using a wooden spoon to break the beef into crumbles, for about 10 minutes, until no pink remains.
Drain excess grease then stir in the marinara sauce. Turn the heat to low and simmer for 15 minutes.
Meanwhile, make the alfredo sauce. In a large skillet, melt the butter over medium heat. Add the garlic and cook for 30 seconds.
Stir in the heavy cream, parmesan, salt and pepper. Cook until the cheese has melted and the sauce thickens slightly, 10-15 minutes.
Add the cooked spaghetti to the alfredo sauce and stir well.
Transfer the pasta to the prepared casserole dish. Spread the meat sauce evenly over the pasta.
Top with the mozzarella and parmesan cheese. Bake uncovered for 15 minutes, until the cheese is melted.
Let cool for a few minutes before serving. Garnish with parsley.