Heat oven to 400°F. Line cookie sheet with foil or cooking parchment paper; spray foil or paper with cooking spray.
In medium microwavable bowl, mix 1/4 cup honey mustard, the butter and garlic salt. Microwave uncovered on High 45 to 60 seconds or until butter is melted.
Place bread crumbs in large resealable plastic food-storage bag. Add chicken pieces to mustard mixture; stir to coat. Shake chicken pieces in bag of bread crumbs until coated. Place on cookie sheet. Discard any remaining honey mustard and bread crumbs.
Bake 20 to 25 minutes or until no longer pink in center. Serve with additional honey mustard.