Ingredients

• 1 slice leftover meatloaf
• 1 tablespoon margarine
• 2 slices bread
• 1 teaspoon ketchup, or to taste
• 3 slices Cheddar cheese
• 1/2 teaspoon prepared yellow mustard, or to taste (optional)

Instructions

1. Place meatloaf on a microwave-safe plate; cook in the microwave on High, 30 seconds at a time, until heated through.
2. Melt margarine in a non-stick skillet over medium heat. Place both bread slices in skillet over melted margarine. Build sandwich on bread slice in this order: ketchup, 1 slice Cheddar cheese, warm meatloaf slice, and mustard. Flip second slice of bread over onto sandwich; cook until bottom of sandwich is lightly browned, about 2 minutes.
3. Flip sandwich with a spatula and place 1 slice Cheddar cheese on top; continue cooking until cheese melts slightly, about 1 minute. Flip sandwich over and lay remaining slice of cheese on top; cook until cheese on the bottom of sandwich is melted and crisp, about 2 minutes. Turn sandwich over; cook until cheese is melted and crisp, about 2 minutes.