Place the butter and sugar in a bowl and whisk, adding the eggs, yoghurt, vanilla and cinnamon. Mix well.
Add the flour, bicarbonate of soda and baking powder and mix together.
Add the blueberries, gently folding them into the mixture.
Meanwhile, preheat the oven to 170oC/Gas Mark 3 and bake for approximately 50-60 minutes, or until golden brown and cooked through.
Leave to cool. Enjoy!