Method

• 1.
  Preheat oven to 160°C. Grease 2 x 20cm round cake pans and line the bases and sides with baking paper.
• 2.
  Place butter and sugar in a stand mixer with the paddle attachment and beat until thick and pale. Add eggs, one at a time, beating well after each addition. Fold in sour cream, flours, vanilla and lemon zest.
• 3.
  Divide mixture between prepared pans and bake for 45-50 minutes until a skewer inserted into the centre of the cakes comes out clean. Stand in pans for 15 minutes before turning onto a wire rack to cool completely.
• 4.
  Once cool, use a serrated knife to trim the top of each cake to level, if required, then cut each cake in half horizontally. Enclose in plastic wrap and set aside until required.
• 5.
  For the white chocolate ganache, place chocolate in a heatproof bowl. Heat cream in a small saucepan over medium-low heat, then pour over the chocolate. Stand for 5 minutes, then stir until smooth. Set aside to cool completely.
• 6.
  Meanwhile, for the passionfruit lemon icing, place all ingredients in a bowl and whisk to combine. Set aside.
• 7.
  For the lemon mascarpone cream, place cream and vanilla in a stand mixer fitted with the whisk attachment. Whisk to soft peaks, then add mascarpone and whisk for 1-2 minutes until thickened. Fold through lemon zest and set aside.
• 8.
  To assemble, place one cake layer on a serving plate. Top with one-quarter of the white chocolate ganache, one-quarter of the mascarpone cream, and 1 tbs passionfruit pulp.
• 9.
  Repeat layering with cake, ganache, cream and passionfruit pulp, finishing with a mascarpone cream layer. Drizzle passionfruit lemon icing over the top, and scatter with toasted coconut flakes, to serve.