In 2-cup glass measuring cup, mix honey, balsamic vinegar, butter and garlic powder. Microwave uncovered on High 1 minute; stir. Microwave 30 seconds; stir. Mixture should be dark, bubbly and very slightly cling to a spoon when stirred. If necessary, heat in additional 15-second increments (2 to 3 minutes total microwave time), stirring after each. (Do not overheat; glaze will continue to thicken as it cools.) Reserve 2 tablespoons of the glaze for brushing on chicken, and keep remaining glaze for serving.