Mix the flour well with the egg yolk and milk and stir in the stiffly beaten snow. Heat the fat in the frying pan and pour in the batter to a thickness of about 1 cm. Fry on one side, then turn to the other side and break into small pieces with a fork. Bake for a short time, then place in a suitable bowl with the lid closed to keep warm, as the pancake still needs a little time to set. Serve sprinkled with sugar, accompanied by juice or compote.