Chop onion. Now’s the time to cook the bacon if you haven’t already, and set aside.
Bring a large pot of water to a boil. Add tortellini and cook 3 min, until floating. Drain and set aside.
In a 12-inch cast iron skillet, cook ground beef, garlic, and onion until no longer pink, breaking meat apart. Drain grease (into the trash, not down the sink).
Stir in cooked tortellini, diced tomatoes, ⅔ of cheese, and ⅔ of bacon.
Top with remaining cheese and bacon. Cover and cook for about 5 min, until cheese is melted. This creates a nice topping.