I bought loads of white chocolate on sale, then wondered what to do with it. This GF sponge with its citrussy-sweet frosting was just the ticket. Pictured is a layer cake, but cupcakes are an option (see footnote).
Lemon and basil are perfect partners, but if you’re in the mood for mint, please do use that instead – I tried that too, and it’s equally tasty.
Serves: 12 -18
For the cake:
- 1 unwaxed lemon, zest and juice (see Cake Step 2)
- 280g gluten-free flour
- 130g caster sugar – golden or white
- 5 tsp gluten-free baking powder
- 1 heaped tsp dried basil (plus extra for decoration) – see footnote for fresh
- 6 large eggs, separated (they should total 370g-400g when weighed in their shells)
- 125ml (120g if weighing) vegetable oil
- 160ml / 160g water
- Butter, to grease tin
For the white chocolate buttercream:
- 2 unwaxed lemons, zest and juice (see Cake Step 2)
- 100g white chocolate, broken into pieces
+ additional white chocolate (10g or so), to decorate
- 200g unsalted butter, cubed and softened
- 1 tablespoon vanilla extract
- 450g icing sugar – sift, if required, after measuring
- Splash of full-fat milk (or cream) if needed
- A round, deep-sided cake tin 26cm (10″) or so in diameter
- Baking/parchment paper cut to line tin
- 3 large mixing bowls
- Electric mixer (hand-held or stand)
- Spatula or large metal spoon for folding
- Oven-safe plate
- A pot which fits 1 mixing bowl on top
- Cooling rack
- Preheat oven to 180 C (160 C fan-assisted). Grease your tin and line the bottom and sides with baking paper.
- Zest and juice all 3 lemons from both cake and frosting ingredients. You’ll need 1 x zest and 2 x juice for the cake; reserve 2 x zest and 1 x juice for the buttercream.
- In the first bowl, mix the flour, sugar, baking powder, and basil with a fork.
- In the second bowl, whisk the egg whites to stiff peaks, starting at low speed and gradually increasing to high speed as the colour and texture change.
- In the third bowl (no need to wash the beaters), whisk the egg yolks with the lemon juice, zest, oil, and water until doubled in volume and fluffy; again, start at low speed and gradually increase to high speed.
- Add the yolk mixture to the dry ingredients and fold together 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. Bake in the 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 its tin on a cooling rack (GF cakes can be too delicate to turn out of the tin while still hot).
White chocolate buttercream:
- When the cake has baked, turn the oven off. Spread 1/2 of the lemon zest on an oven-safe plate, breaking up any clumps, and put in the oven (door ajar) for 30 minutes to dry out as the oven cools.
- Heat the 100g broken white chocolate in a bowl over a pot of simmering water on the hob, until melted. Ensure the bottom of the bowl doesn’t touch the water.
- With the mixer on low, whip up the butter, vanilla, lemon juice, and remaining lemon zest until fluffy, gradually increasing the speed to medium-high. Add the icing sugar some at a time, beating continuously on low speed. Once all in, scrape down the bowl really well, add the melted white chocolate, and stir manually until fully combined. If it seems too stiff for you, add a splash of full-fat milk (or cream); continue stirring until well mixed, and at your preferred consistency for spreading.
- Slice the cooled cake in half horizontally (see footnote). Spread 1/4 of the frosting over the top of the bottom layer; sprinkle over 1/2 of the dried lemon zest and also some basil; then place the top layer on. Spread the top and sides with the remaining frosting, then sprinkle over the remaining dried lemon zest and some more basil.
- Make the additional white chocolate into curls (using a vegetable peeler or knife), or grate it, and sprinkle over the top.
Layer Cake Tips
I’m hopeless at slicing cakes in half horizontally, so when making a layer cake, I bake the layers separately. After pouring the cake mix into the tins, I smooth a depression into the centre of one of them – this helps to make a flat rise for the one that becomes the base layer.
You could also make 18 – 24 cupcakes from this recipe (depending on size). Line two 12-hole muffin tins with paper cases, and check after 15 minutes’ baking to see if they’re done. Remove the cases from the tins immediately when out of the oven, and cool on a cooling rack. Frost and decorate as per the instructions.
Dried Herbs v Fresh
If you have fresh basil (or mint), great! The standard substitution is double+ measures; i.e., 2 & a bit tsp of [finely chopped] fresh for 1 tsp of dried.