Grease 2 (9") round cakepans, and dust with cocoa.
Beat cake mix and next 7 ingredients at low speed with an electric mixer 1 minute; then beat at medium speed 2 minutes. Fold in chopped milk chocolate bars. Pour batter into prepared pans.
Bake at 350° for 32 minutes or until cake springs back when lightly touched. Cool cake in pans on wire racks 10 minutes; remove from pans, and cool completely on wire racks. Wrap and chill cake layers at least 1 hour or up to 24 hours. (This step enables you to split cake layers with ease.)
Using a serrated knife, slice cake layers in half horizontally to make 4 layers. Place 1 layer, cut side up, on a cake plate. Spread with 1/2 cup cream cheese frosting; sprinkle with one-fourth of chopped cheesecake bites. Repeat procedure with remaining 3 layers, frosting, and cheesecake bites, omitting cheesecake bites on top of last layer. Frost sides and top of cake with remaining frosting. Drizzle desired amount of caramel sauce over cake, letting it drip down sides. Chill until ready to serve. Decorate cake with rolled wafer cookies and remaining chopped cheesecake bites. Store in refrigerator.