Prepare and bake brownies according to package directions for cake-like brownies, using a greased 13x9-in. baking pan. Cool completely on a wire rack.
Beat milk and pudding mixes on low speed for 2 minutes. Let stand for 2 minutes. Fold in whipped topping.
Cut the brownies into 1-in. cubes; place half in a 3-qt. glass trifle bowl. Cover with half of the pudding. Repeat layers. Sprinkle with chopped candy bars.