Preparation time less than 30 mins Cooking time 30 mins to 1 hour Ingredients For the sponge 225g/8oz unsalted butter, at room temperature, plus extra for greasing 225g/8oz golden caster sugar 4 free-range eggs 1 lime, zest and juice 50g/2oz desiccated coconut, toasted 200g/7oz self-raising flour splash milk (optional)   For the custard 6 free-range [...]