Blueberry

• 1 egg
• 3/4 blueberries
• 130 gr flour
• 65 gr sugar
• 60 ml low-fat buttermilk
• 50 gr unpeeled tart apple (minced)
• 45 gr butter
• 5 gr baking powder
• 2 gr baking soda
• 2 gr cinnamon (ground)