Beat room temperature butter for 5 minutes until light, airy and creamy.
Add in the can of dulce de leche and continue beating for around 10-15 minutes until it is light, and volumunous.
Spoon the cream onto the first cake wafer and spread thoroughly. Make sure to scrape it into the wafer indents throughout the sheet. The cream should be divided into about 10 parts, for the 9 wafers in the package and for some on top.
Put the next layer on and repeat adding the cream.
Continue until the last wafer. Spread the remaining cream onto the last wafer.
Spread the chopped hazelnuts on the top of the cake.
Refrigerate for 4 hours or overnight.