Turn the oven off. Allow the cake to cool in the oven with the door closed for 30 minutes. Remove from the oven and cool completely. While the cake is cooling, make the coffee syrup. Place the liqueur ...
Add the hazelnuts and swirl to coat them in the syrup, then quickly tip the mixture onto the baking sheet. Leave to cool and harden. To make the buttercream, dissolve the coffee in 1 tablespoon of ...