“This is a very fresh, beautifully textured lemon cake – no one would even guess it is gluten-free,” says Rosie. “Orange or lime zest can be used instead for different variations.”

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1. Preheat the oven to 160ºC fan (180ºC conventional).
2. Grease a 1lb loaf tin or a 7in round tin (with oil spray or with margarine).
3. Melt the chocolate (short bursts on a low microwave setting, or in a bowl over a pan of lightly simmering water).
4. Add the caster sugar and margarine to the bowl and beat until pale and fluffy.
5. Add the eggs, flour, zest, xanthan gum (if needed), baking powder and white chocolate and mix well.
6. Transfer the mixture to the loaf/cake tin and level the top.
7. Bake for 40-45min then check – if a skewer comes out of the centre of the cake clean, it’s done. If not, give the cake another 5min and check again.
8. Prepare the drizzle by mixing the lemon juice and caster sugar.
9. Transfer the cake to a cooling rack after cooling in the tin for 10min.
10. Use a cocktail stick to make lots of small holes in the top of the cake, then pour the drizzle over.
11. Leave the cake to cool completely before melting the chocolate.
12. Use a teaspoon to drizzle chocolate in fine lines across the top of the cake.
13. Sprinkle a mix of zest and caster sugar on top.