POUR milk into large bowl. Add dry pudding mixes. Beat with wire whisk 2 minutes or until well blended. Gently stir in whipped topping.
PLACE 7 of the cake slices in 13x9-inch pan; drizzle with half of the chocolate syrup. Cover with layers of half each of the pudding mixture and chopped chocolate bars. Top with layers of remaining cake slices, chocolate syrup and pudding mixture; sprinkle with remaining chopped chocolate bars.
SERVE immediately or cover and refrigerate until ready to serve. Store leftover dessert in refrigerator.