Heat oven to 375°F. Spread butter onto cut-sides of sandwich rounds. Place onto ungreased baking sheet, cut-sides up. Bake 6-8 minutes, turning once, or until lightly toasted on both sides.
Place 1 slice yellow cheese onto cut-side of each round. Cut 8 shapes from white cheese using 1 1/2- to 2-inch Halloween-shaped cookie cutters. Place 1 cheese shape over each yellow cheese-topped sandwich round. Bake 2-3 minutes or until completely melted.
Create eyes and nose using cranberries, if desired.
Chop trimmings of white cheese and save for use in salads or sandwich fillings.