For the blackberry patties, mix milk, flour, sugar, salt and egg to a firm dough. Carefully fold in the blueberries.
Heat the clarified butter in a pan and pour a large tablespoon of batter into each pan. Flatten slightly and fry to form a Datscherl on both sides.
Let the Datscherl drain a little on a paper towel and serve warm sprinkled with powdered sugar.