Place beef, onions, and garlic in a skillet over medium-high heat and cook until meat is browned. Drain off the fat and then add in the marinara sauce, beef broth, and noodles. Bring to a boil, and then reduce heat to low and let it simmer uncovered for 15-20 minutes or until noodles are al dente.
Stir in half of the mozzarella cheese and then dot the top with ricotta. Sprinkle with remaining mozzarella, cover and let it sit for 2-4 minutes until cheese melts. Serve immediately.