How to make
Beat the butter with 1 cup powdered sugar into fluffy cream. Add the ground walnuts, flour and while stirring carefully add the four whites, that you've beaten well into snow.
Bake at 360°F (180 °C) in a rectangular medium-sized oven dish. Immediately after baking, cover it with the glaze: the four egg yolks beaten well with a cup of powdered sugar.
Leave it overnight. Cut it into diamonds or rectangles. Serve with ice cream, sprinkled with the nuts.
