Preheat oven to 350°F.
Bring a large pot of salted water to a boil. Cook spaghetti according to package directions until al dente. Drain and set aside.
In a large dutch oven or braiser over medium high heat, brown the hamburger meat until fully cooked. Drain excess grease if needed.
Stir the marinara into the cooked beef and let simmer for 3–5 minutes. Transfer to a saucepan to continue simmering, wipe out dutch oven. (You can skip this and just start the marinara in a saucepan oven if you prefer)
In the same dutch oven, melt the butter over medium heat.
Whisk in the Dijon mustard, Cowboy Butter seasoning, garlic powder, parsley, and paprika. Cook for about 1 minute until fragrant.
Slowly pour in 2 cups heavy cream, stirring continuously. Bring to a gentle simmer and cook for 3–5 minutes until slightly thickened.
Gradually stir in 2–3 cups Parmesan cheese until melted and smooth.
Add 1 cup mozzarella cheese and stir until fully melted and creamy.
Now pour in your spaghetti noodles and combine with the alfredo.
Pour the meat sauce over the spaghetti/alfredo mixture and do not stir.
Top with additional mozzarella cheese.
Bake uncovered for 10-15 minutes, or until bubbly and the cheese is melted and lightly golden.
Broil for a minute or two if preferred.