Mix the flour, salt, baking powder and sodium bicarbonate in a bowl. Whisk together the sour milk, butter, egg yolk and maple syrup, stir into the flour mixture. Beat the egg white with the salt until stiff, fold in carefully.
To cook the pancakes
Heat a little clarified butter in a non-stick frying pan. Pour enough batter into the pan to make a pancake approx. 5 mm thick and approx. 10 cm in diameter. Reduce the heat. Once the underside is cooked and separates from the pan, turn the pancake, finish cooking, cover and set aside. Prepare the remaining pancakes in the same way. Plate up the pancakes, drizzle with the maple syrup.