Preheat oven to 350º. In a medium bowl, mix the egg whites, the crushed walnuts and the confectioners sugar. And set aside. In a large bowl, mix the egg yolks, butter and the flour until smooth. Divide dough into 3 pieces. Roll out a portion at a time into a 4”x12” long and 1/2” thick piece. Spread with filling and cut into 2” long pieces and form into a crescent, closing both ends by pinching, Bake 8-10 min or until lightly brown, sprinkle after cooling if desired with confectioners sugar.