Heat the olive oil in a large, deep skillet over medium-high heat. Add the ground beef and cook, breaking it up with a spoon, until browned. Drain off any excess grease.
Add the chopped onion to the skillet and cook until softened, about 4 minutes.
Stir in the minced garlic, Italian seasoning, salt, and pepper. Cook for 1 minute until the garlic is fragrant.
Pour in the beef broth and bring the mixture to a boil.
Add the dry pasta to the skillet. Reduce the heat to medium-low, cover the skillet, and simmer for 12 to 15 minutes, or until the pasta is tender and most of the liquid is absorbed. Stir occasionally to prevent sticking.
Remove the skillet from the heat. Stir in the heavy cream.
Add the cheddar cheese and mozzarella cheese. Stir until the cheese is completely melted and the sauce is creamy.
Serve immediately, garnished with fresh parsley.
Notes
Use a sturdy skillet with a tight-fitting lid for best results during the simmering phase.
If the sauce seems too thick after adding the cheese, add a splash more broth or milk until you reach your desired consistency.