Put the oil, butter, and chopped onion in a large, heavy bottomed pot and turn the heat on to medium. Cook the onion until it has become translucent.
Add ground beef, salt, pepper, garlic powder, and paprika and sauté meat until it has lost its pink color, breaking it up with the back of a spoon as it cooks.
Stir in one cup of milk and let the mixture simmer gently, stirring frequently, until the milk has bubbled away completely.
Add nutmeg and tomato paste and stir to combine.
Add pasta, remaining milk, and beef broth and bring the contents of the pot to a boil. Reduce heat to low and simmer, stirring regularly to prevent the pasta from sticking to the bottom of the pan. Continue to cook until the pasta is al dente and most - but not all! - of the liquid has been absorbed.
Stir in cheese and remove from heat.
Garnish with freshly chopped parsley and enjoy!