Mix and bake cake according to package directions in 9" cake pans. Cool completely. Mix confectioners sugar, softened cream cheese and 3 tbsp. of Cool Whip whipped topping. Blend well. Spread 1/2 the mixture on bottom layer. Spread 1/2 can cherry pie filling over it. Place on top layer of cake. Secure with toothpicks, if necessary. Spread remaining cherry filling over all. But don't add cherries yet. Blend the pudding mix with the remaining Cool Whip topping. Add a small amount of milk if it seems too stiff. Frost sides of cake and build a rim at the top of the cake to hold the remaining cherry pie filling.