Citrus layer cake

1. Preheat the oven to 190ºC, gas mark 5 and grease and line 3 x 18cm cake tins with baking parchment.

2. Using a handheld electric whisk or stand mixer, cream together the butter and sugar until light and fluffy. Add the eggs one at a time, whisking after each addition.

3. In a small bowl, combine the flour, baking powder and the lime, lemon and grapefruit zests. Add these dry ingredients to the egg mixture a few tbsp at a time and continue to mix until a smooth batter forms.

4. Divide the mixture between the tins and use a spatula to smooth over the top. Bake for 20-25 minutes or until golden and well risen. A skewer inserted into the centre of each one should come out clean. Allow to cool briefly in the tins before turning onto a wire rack to cool completely.

5. While the cakes cool, make the dried citrus decoration (if using). Turn the oven down to 120ºC, gas mark ½ and line a large baking tray with parchment paper. Slice the grapefruit, lemon and lime as thinly as possible and arrange on the tray. Sprinkle each slice with sugar, then bake for 1 hour 30 minutes-2 hours, turning halfway, until dry to the touch (the grapefruit may take longer than the lemon and lime). Allow to cool before using. You can store the slices in an airtight container for up to 2 days before decorating.

6. For the filling, beat together the soft butter with ½ the icing sugar using an electric whisk until smooth, then add the remaining sugar and citrus juice (use a mix of all 3, or just 1 if you prefer). Beat for a few minutes until light and fluffy, then set aside.

7. To assemble the cake, smear a plate or cake stand with a small amount of buttercream, then place the bottom layer on top. Cover with ¼ of the remaining buttercream and ½ the lemon curd, then place the next layer of cake on top. Repeat, topping with the final cake. Chill the whole cake for 30 minutes to firm up before you ice the outside.

8. Once cold, cover the top and sides of the cake using the remaining icing to create a semi-naked effect. Arrange the dried citrus slices in a cascade down the side and over the top. Serve immediately, or store in an airtight container for up to 3 days.