Beat the butter at medium speed for a minute. Turn the speed down to low and slowly add the dulce de leche. (1 can plus the remaining unused can of dulce de leche from the batter).
Place the bottom part of one of the cake and this will be 1st layer. Set it down same way as is with the part that was cut facing up. Spread a generous portion of the cream.
Place the 2nd layer with the top facing down and the middle part facing up. Cover with cream. Repeat with remaining layers and cream.
Reserve about two tablespoon of cream so it can be used for decor, this is optional.
Chop 1 3/4 cups chocolate waters. Grind or blend wafers until they are very fine.
Generously cover the top of cake with the some wafers.
Place the leftover cream in a small Ziploc, snip off an edge of the bag and drizzle atop cake. I just make zigzag lines sideways.