Preheat the oven to 350 degrees F (175 degrees C). Butter one side of each slice of bread, and press each slice butter-side down into the cups of a muffin tin.Advertisement
In a medium bowl, mix together the ground beef, egg, onion, cream of mushroom soup, salt and pepper until well blended. Fill each bread cup with the mixture. Sprinkle shredded Cheddar cheese over the tops.
Bake for 30 minutes in the preheated oven, or until meat is cooked through.