Mix the flour, chestnut flour, baking powder, sugar, oil, salt, cream and mineral water with an electric mixer until smooth. Quarter the apple, peel and cut into thin slices. Meanwhile, preheat a non-stick frying pan without fat. Pour the batter into the pan in portions and spread the apple evenly on top. Fry the pancakes on both sides until they turn golden brown. Mix the cinnamon and sugar and serve with the pancakes.