Preheat the oven to 180°C, fan 160°C, gas 4. Grease and line the bases of 2x20cm round cake tins. Put the Butterlicious, golden caster sugar and vanilla in a large bowl. Using an electric whisk, beat until light and fluffy. Gradually add the eggs, beating well after each addition.
Sift in the flour and baking powder, then add the coconut, soured cream and lime zest. Use a metal spoon to fold everything in.
Divide the mixture between the prepared tins and level the surfaces. Bake for 20-25 minutes until risen, golden and just firm to the touch. Cool for 5 minutes, then turn out on to a wire rack to cool completely.
Make the frosting: put the white caster sugar, egg whites and 1 tablespoon of water into a large heatproof bowl set over a pan of simmering water – the bottom should not touch the water. Whisk using an electric hand-held whisk until thickened. Remove from the heat and keep whisking for 2-3 minutes until firm and glossy.
Spread 3 tablespoons of frosting over the top of one cake, and put two-thirds of the raspberries on top of the frosting. Top with the other cake and cover with the remaining frosting. Decorate with the remaining berries and a sprinkling of silver lustre.