In a large skillet, heat olive oil over medium heat. Add onions and bell peppers. Cook until soft.
Add garlic and ground beef. Cook until browned. Drain excess grease.
Stir in beef broth and milk. Bring to a low boil.
Add pasta. Stir and simmer until pasta is tender and most of the liquid is absorbed (about 12–15 minutes).
Turn off the heat. Stir in shredded cheese until melted and creamy.
Serve warm and garnish with extra cheese or parsley, if desired.