1. Spread the 18 bread slices with softened butter or margarine; arrange in 3 rows of 6 slices each. Spread first row with Ham Filling. Cover with slices in second row, butter-side down. Spread unbuffered sides with Cheese Filling. Top with remaining slices, butter-side down, to make 6 sandwiches. Wrap in waxed paper, foil or plastic wrap; chill.
2. Unwrap sandwiches; trim crusts if you wish; cut each sandwich into quarters.