If you're using plain baking flour, be sure to add some gf baking powder and baking soda (sodium bicarbonate).
For this quantity of flour, I used 1 tsp of baking powder and 1/2 tsp of baking soda. I also added some Xanthum gum to help with structure (about 1/2 tsp).
Ingredients (serves 10 generously)
- 175g butter, softened
- 125g caster sugar
- finely grated zest of 3 lemons
- 3 med eggs
- 175g self-raising flour
- pinch of sea salt
- splash of milk (optional)
- 80g icing sugar
- some lemon juice
- Put butter and sugar in a large bowl and beat for 10 minutes with Kitchenaid or other electric blender - 5 min will do but 10 better.
- Add zest and eggs, one at a time and with a spoonful of flour in between to help binding
- Sift remaining flour and salt into blow and fold. Add a little milk if mixture doesn't drop easily from spoon.
- Spoon into loaf tin (I used 2lb, fitted comfortably, though non-gf might rise more) and smooth top. Don't forget to line with parchment paper.
- Bake at 170C for 40-45 minutes.
- When done, mix icing sugar and enough lemon juice make pliable and drizzle over cake in the loaf tin. First though, make plenty of 'holes' in the cake with a skewer to let the icing soak in well.
- Leave into tin until cool, then turn out and slice.
By my reckoning, a decent slice weighs in at 30g CHO but go very light on the icing sugar and that can be nearer to 20g.