Hungarian nut crescents

Dough:
1 c butter
1 c shortening
6 1/4 c flour
2 tb yeast
1 pt sour cream
3 egg yolks
1 pn salt
Filling:
1/2 lb ground walnuts
1 1/4 c sugar
1/4 ts cinnamon
1 ts vanilla
3 egg whites, stiffly beaten
Egg wash:
1 egg yolk
Few drops water
Extra sugar

In a bowl, cut the butter and shortening into the flour until the mixture is crumbly. In a separate bowl, mix the yeast into sour cream, then add egg yolks and salt. Combine with the flour mixture. Mix until smooth and the sides of the bowl are clean. Form into a large ball and chill, covered, overnight. To make filling, mix walnuts, sugar, cinnamon, vanilla and stiffly beaten egg whites together in a bowl. To make egg wash mix egg yolk and few drops of water in a small bowl. Preheat oven to 350. Sprinkle granulated sugar onto a pastry board. Divide the dough into six portions. Work with one portion at a time, refrigerating the dough you are not using. Roll out the dough to 1/8-inch thick and sprinkle with more sugar. Cut into 2 x 2" squares. Place a bit of the nut filling along one end of the square and roll up. Form into a crescent. Place seam side down on a greased cookie sheet. Paint with egg wash. Bake at 350
for 15-20 minutes. Remove from oven and cool on wire racks.