Prep: Cut 8 (8-inch) squares of aluminum foil.
Protect the bread: Spread a thin layer of butter on the cut sides of both the tops and bottoms of each kaiser roll.
Build the sandwiches: Start with dividing the chicken evenly onto the bottom halves of the rolls. Spread a thin layer of mustard onto the chicken. Top with the ham, cheese, and finally the bacon before closing the sandwiches with the top of each roll.
Freeze: Wrap each sandwich in a piece of foil. Place the sandwiches in a gallon zip-top bag labeled with the reheating instructions. Freeze.
Reheat: Arrange a rack in the middle of the oven and heat to 350°F. Unwrap the sandwiches from the foil and place on a parchment-lined baking sheet. Bake until the cheese is melted and the meat is heated through, 15 to 20 minutes.
