Rugalach

In large mixing bowl, beat butter with an electric mixer on medium to high speed for 30 seconds. Add sour cream and egg yolk. Beat until combined. Using a wooden spoon, stir in flour until combined. (Dough will be sticky.) Divide dough into fourths. Cover and chill for at least 1 hour or until dough is easy to handle.

In a small bowl, combine sugar, chocolate pieces and cinnamon; set aside (or if desired, make Apricot-Walnut Filling).

On lightly floured surface, roll one-fourth of the dough into a 10-inch circle. Spread 1/4 of the filling over circle. Cut dough into 12 wedges. Roll up each wedge, starting at wide end. Repeat with remaining dough and filling.

Place cookies, tip sides down, about 2 inches apart on foil-lined cookie sheets. Bake in a 350 degree oven for 20 minutes or until golden brown. Transfer to wire racks to cool. If you like, sprinkle with powdered sugar.