- For the cake: Preheat oven to 180 C / 160 C Fan / Gas 4. Grease a round, deep-sided 26cm (10 inch) cake tin and line the bottom and sides with baking paper. You will also need 3 mixing bowls.
- In the first bowl, mix the flour, caster sugar, baking powder and desiccated coconut together with a fork.
- In the second bowl, whisk the egg whites with an electric beater to stiff peaks, starting at low speed and gradually increasing to high speed.
- In the third bowl, whisk the egg yolks, lime juice, zest, oil and water with an electric beater until doubled in volume and fluffy, starting at low speed and gradually increasing to high. (No need to clean the beaters from whisking the egg whites.)
- Add the yolk mixture to the dry ingredients and fold together with a spatula until fully combined and smooth.
- Add one-third of the egg whites, folding briskly, to loosen the mixture. Then add the rest of the whites and fold carefully until no white lumps or streaks remain.
- Pour the batter into your prepared tin and smooth the top with the spatula. Bake in the preheated oven for 20 – 25 minutes, turning halfway through for even baking, until a skewer inserted in the centre comes out clean. Cool the cake in the tin on a cooling rack (gluten free cakes can be too delicate to turn out of the tin while still hot).
- For the coconut cream frosting: When the cake has baked, turn the oven off. Spread the lime zest on an oven-safe plate, breaking up any clumps, and put in the oven for 30 minutes to dry out as the oven cools.
- Put the coconut oil into your mixing bowl, and break up any large lumps with your wooden spoon. Microwave on the defrost (or lowest) setting for 1 minute, then see if it’s pliable enough to beat as if you were creaming butter. If not, zap for 20 seconds more, and test again; continue until it’s softened enough.
- With the mixer on low, add about 3/4 of the double cream, the rum (if using), vanilla, and lime juice, one item at a time, to the softened coconut oil, mixing well after each addition. Scrape down the bowl really well, and beat about 2 minutes on medium speed.
- Add the icing sugar gradually, beating continuously on low speed. Once all in, scrape down the bowl again and continue beating on medium speed about 2 minutes.
- If the mixture is too stiff for you, add the rest of the cream 1 tablespoon at a time, mixing at medium speed for about 1 minute after each addition, until you have the consistency you want.
- Slice the cooled cake in half horizontally. Spread 1/4 of the frosting over the bottom layer, then sprinkle some desiccated coconut over. Put on the top cake layer, and spread the rest of the frosting over the top and sides. Sprinkle over more desiccated coconut, then the dried lime zest, then the coconut curls to decorate.
Raw coconut oil is sold as a solid (in a jar) in most supermarkets. When baked, it doesn’t have a strong coconut taste, and it’s lactose-free so it’s excellent for someone avoiding butter. However, you can use unsalted butter in the frosting if you prefer; it won't be dairy-free of course, and you’ll need to add coconut flavouring.
See it on my blog
See this recipe in more detail, plus more GF recipes, on my blog