Ingredients

Step by step

1. Preheat the oven to 180°C, fan 160°C, gas 4. Grease and line 3 x 18cm loose-bottomed cake tins. Beat the butter and sugar together until light and fluffy. Add the eggs one at a time, beating well between each addition. Sift together the flour, cocoa powder and baking powder and carefully fold through the cake mixture, with a pinch of salt. Finally stir through the ground hazelnuts, buttermilk and vanilla.
2. Divide the mixture between the tins and bake in the oven for 35-40 minutes, or until a skewer inserted comes out clean. Remove from the oven and immediately drizzle each sponge with 1 tablespoon of the hazelnut syrup. Leave to cool in the tins for 10 minutes, before removing and allowing to cool completely on wire racks.
3. For the buttercream, put the white chocolate in a heatproof bowl and place over a pan of simmering water. Stir gently until the chocolate has melted. Remove from the heat and leave to cool slightly. In a separate bowl, beat together the butter and icing sugar until you have a smooth buttercream. Beat in the white chocolate.
4. To decorate, level the tops of all three cakes. Place the first of the cakes on a board or cake stand and top with a layer of buttercream. Sandwich with the second cake and layer with more buttercream before topping with the final cake. Turn the final cake upside down before sitting on top so that the top of the cake is very flat.
5. Cover the top and sides of the cake with a first layer of icing, making sure it isn’t too thick, but thick enough to hold the decorations. Then, using a palette knife cover the bottom third and top third with a thick layer of icing (about 7mm thick), leaving a rough channel around the middle which isn’t iced – this will be the fault-line that you fill with your chocolate decorations. It doesn’t matter if the channel is different widths and heights, it will add to the final look of the cake. Taking a large palette knife, skim around the circumference of the cake to smooth the top and bottom layers of icing, leaving the fault-line around the middle. Chill in the fridge for around 30 minutes, so the icing is firm.
6. Carefully cut the Galaxy and Kinder eggs in half with a sharp knife, then use these to fill the fault-line. Fill the gaps between the eggs with the chocolate sprinkles until the line is completely filled.
   
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