PREHEAT oven to 350° F. Grease 9- or 10-inch-round baking pan.
PREPARE brownie batter according to package directions; stir in chopped Butterfinger. Spoon into prepared pan.
BEAT cream cheese, sugar and milk in small mixer bowl until smooth. Pipe cream cheese mixture into concentric circles over brownie batter. Using wooden pick or tip of knife, pull tip through cream cheese from center to last circle to create a spiderweb effect.
BAKE for 40 minutes or until wooden pick inserted near center comes out almost clean. Cool completely in pan on wire rack. Cut into wedges using wet knife.