Preheat oven to 180C.

Whip eggs and sugar in stand mixer for 7-8 minutes on high speed until light and moussey.

Add coffee powder, salt, baking powder and vanilla extract and whisk on high for another minute.

While the batter is whisking, prepare the tin. Line the base and sides of a 6" round baking tin with parchment paper. Grease and flour it too.

Once the mixture is about double, gently sift in the flour in three lots, folding in gently in figure 8 movements. Take care not to release the beaten in air.

Gently turn batter into the prepared tin and even out. Bake for 25-30 minutes until well risen and light golden brown. The top should spring back when touched with fingertips, or do a toothpick test.

Sift some sugar over the top, and gently tun cake onto the cooling rack, and carefully peel off the parchment paper. Let the cake cool completely, then cut into two horizontal layers.

Place all ingredients in a clean, chilled bowl and whip to stiff peaks. Use about 2/3 to sandwich the layers, and roughly pile the rest on top, creating peaks with an offset spatula. Top with dark chocolate shavings

Measure out a strip of parchment paper to go around the cake. Lay out flat.

Melt the chocolate over a double boiler or in the microwave and transfer to a piping bag. Pipe designs all over the border. If the weather is warm, place the strip in the fridge for 10-15 minutes. When just about to set, place snugly around the cake, pressing into place ever so gently.

Stand the cake in the fridge for about 30 minutes for the chocolate to harden, then gently peel off the parchment.