FOR each serving: Spread 2 bread slices evenly with 1 Tbsp. mustard. Fill with 3 Tbsp. cheese, 1 oz. ham slices, 1/3 cup chicken, 2 pickle slices and additional 3 Tbsp. cheese. Brush outside of sandwich evenly with 1 Tbsp. butter.
GRILL on flat-top griddle heated to 350ºF for 2 min. on each side or until cheese is melted and sandwich is golden brown on both sides. Cut in half.