In a large mixing bowl, combine the cake mix, brown sugar, eggs and butter. Beat on low speed for 2 minutes, scraping bowl occasionally. Stir in chopped candy. Spread into an ungreased 13-in.x 9-in.x 2-in. baking pan. Bake at 350 degrees F for 25-30 min. or until a toothpick comes out clean. Cool on a wire rack. Cut into squares.