Strawberry and raspberry cakes

Ingredients – for 6 little cakes

• 65g unsalted butter, softened (out of the fridge in advance)
• 52g caster sugar
• 80g self-raising flour
• third of a tsp baking powder
• 1 medium egg
• 1 heaped dessertspoon (20g) Greek yoghurt
• A few drops of good vanilla essence
• 40g raspberries or strawberries or a mixture
• 6 muffin cases