Yugoslav Kifle

Heat sour cream and water until warm (100 to 110 degrees F). Sprinkle in yeast; stir until dissolved

In medium bowl, combine butter and half cup flour. Add sour cream mixture and beat 1 minute at low speed of electric mixer, scraping bowl occasionally. Add egg yolks and quarter cup flour; beat 1 minute at medium speed, scraping bowl occasionally. Stir in enough remaining flour to make a soft dough.

Knead on lightly floured surface until smooth and elastic, about 8 to 10 minutes. Divide dough into 3 equal pieces; cover tightly with plastic wrap. Refrigerate 2 to 24 hours.

On a surface dusted with powdered sugar, roll each piece of dough to a 10-inch circle. Cut each into 8 wedges. Top wide edge of each wedge with about 1 tablespoon Nut Filling. Roll up from wide end to point.

Place on greased baking sheets, with points underneath. Brush with melted butter. Bake at 375 degrees F for 18 to 20 minutes or until golden brown. Remove from baking sheets; cool on wire racks. Sprinkle with powdered sugar while warm, if desired.

For Nut Filling: In bowl, beat egg whites until stiff peaks form. Combine finely chopped walnuts, sugar and vanilla extract. Fold in stiffly beaten egg whites.