Preheat oven to 350 degrees and spray a muffin pan with non-stick cooking spray. Set aside.
Mix together the ground beef, onion, green bell pepper, minced garlic, salt, pepper, oregano, breadcrumbs, and egg together in a medium mixing bowl.
Add ½ cup of the mixture to each muffin slot, trying to round the tops some to resemble muffins. Bake for 25 minutes. Add the ketchup on top using a baster and bake for another 1 minute.
Allow the mini meatloaves to cool for 5 minutes before removing.