Preheat the oven to 180C/ 160C fan/ Gas 4. Grease and line a 1.2 litre loaf tin (22cm x 13cm width, 7cm depth) with baking parchment. Mix together the flour, baking powder, xylitol and lemon zest in a large bowl.
Mix the eggs, sunflower oil, milk and yoghurt together in a separate bowl or jug and stir them into the flour mixture.
Spoon into a tin and smooth the surface. Transfer to the oven immediately, bake on the middle shelf of the oven for 1 hour – 1 hour 10 minutes Check after 50 mins, if the cake is becoming too dark, cover loosely with foil.
Just before the end of cooking time, make the drizzle by heating the lemon juice and xylitol. Stir over a low heat until the xylitol has dissolved. Once the cake is cooked, take it out of the oven and pour over the drizzle.
Cool in the tin before turning it out.
Recipe from bbcgoodfood.com, January 2012 BBC GoodFood Magazine.