Heat oil in large pot over high heat and add garlic and onion, cook for a couple of minutes. Then add bell pepper and cook until onion is translucent.
Add beef and cook, breaking it up as you go. Once the beef is browned, add remaining ingredients (including elbow pasta, but except cheese and parsley). Stir, bring to simmer, then turn the heat down to medium.
Cover and cook for about 12 minutes and remove pot from the burner.
Stir through half the cheese. Taste it and adjust salt and pepper to taste. Top with remaining cheese, put the lid back on and leave until the cheese melts - about 2 minutes.