Warm a skillet over medium heat for 3 to 5 minutes. Place the bread slices on a flat work surface. Spread 1 tablespoon of butter evenly over one side of each slice of bread.
Place one of the bread slices onto the hot skillet, butter side down. Top with the mustard and spread evenly. Top with the slice of cheese, then the meatloaf. Spread the ketchup on top of the meatloaf and top with the remaining bread slice, butter side up.
Cook for 3 to 4 minutes, or until the cheese begins to melt around the edges. Flip sandwich carefully and cook for 3 minutes, or until bread is golden brown. Cut in half and serve immediately!
Notes
For best results, cut a thick slice of meatloaf for this sammy. A minimum of 1-inch-thick meatloaf slices is ideal for optimal meaty flavor.
If cold (cooked) meat seems weird, warm meatloaf slice in the microwave or in a skillet before adding it to the sandwich.
An alternative to creating a grilled cheese sandwich, forego the grilling portion and serve as a cold meatloaf sandwich.
If you have meatloaf sauce leftovers, use this as a spread on the sandwich.
Favorite toppings, condiments or spreads: bbq sauce, hot sauce, any tangy sauce or chopped red onion.
Turn this into an open-faced meatloaf sandwich, if desired, and serve with a fork!