Method

• 1.
  Preheat the oven to 180°C. Grease and line the base and sides of two 20cm springform cake pans with baking paper.

• 2.
  Beat butter and 200g caster sugar in an electric mixer for 5 minutes or until thick and pale. Add eggs, one at a time, beating well after each addition, then add vanilla.
• 3.
  Sift flour, baking powder and baking soda together. In 3 batches, alternately fold the flour mixture and buttermilk into the egg mixture until combined.
• 4.
  Divide the batter between the 2 pans and smooth tops with a palette knife. Bake for 35-40 minutes until golden and a skewer inserted in the centre comes out clean. Cool for 5 minutes in the pan, then transfer to a wire rack to cool completely.
• 5.
  Meanwhile, soak gelatine leaves in a bowl of cold water for 5 minutes.
• 6.
  Puree berries and remaining 1/2 cup (110g) sugar in a small food processor. Strain berry puree through a sieve, pressing down to extract the juice. Place half the strained puree in a saucepan over medium-low heat and cook, stirring, for 3 minutes or until warmed through.
• 7.
  Squeeze excess water from gelatine and add gelatine to the warm puree, stirring to dissolve. Strain into remaining puree and chill for 10minutes. Once cool, fold in the cream. Chill berry mousse for 10 minutes.
• 8.
  Using a serrated knife, trim the top off each cake to give a flat surface. Carefully slice each cake in half horizontally.
• 9.
  Line a clean 20cm cake pan with plastic wrap. Place one cake layer in the pan, brush with one-third of the liqueur and pour over one-third of the mousse. Repeat layers 2 more times, gently pressing down on the cake in between each (the third layer of mousse should come level with the top of the pan). Top with remaining cake layer. Cover with plastic wrap and refrigerate overnight.
• 10.
  For the icing, whisk together sugar, eggwhite, cream of tartar and 1/4 cup (60ml) water in a heatproof bowl. Place over a pan of simmering water (don't let the bowl touch the water) and whisk for 10 minutes or until doubled in volume. (Alternatively, whisk with electric beaters for 6-8 minutes.) Whisk in marshmallow, then transfer to an electric mixer and whisk for 10 minutes or until bowl is cool.
• 11.
  Remove cake from the pan and transfer to a plate. Spread the icing over the top and sides, dust with coconut and decorate with raspberries. Serve immediately or chill until ready to serve.