Heat oven to 190C/170 fan/gas 5 and line a 12-hole bun tin with paper cases. Put the flour, sugar, butter, yogurt, lemon zest and eggs in a bowl and mix with electric beaters until smooth. Spoon a large tablespoon of the mixture into each of the cases, making them as even as possible. Bake for 20-25 mins until the cakes are risen and golden, and a skewer poked into the centre of one comes out clean. Set aside to cool on a wire rack.
Healthy chocolate brownies
Heat the oven to 190C/170C fan/gas 5 and line a shallow 23cm square baking tin with baking parchment. Tip the beans, cocoa, coffee granules, xylitol, vanilla, eggs and yogurt into a large bowl. Blitz using a hand blender until smooth. Or, do this in a food processor. Add the baking powder, then blitz again.