Cut margarine into flour.

Beat egg yolk and combine with sour cream.

Add the egg yolk and sour cream mixture to the flour and margarine mixture.

Mix together and form a ball of dough.

Refrigerate the dough overnight, covered.

Mix sugar, cinnamon, and walnuts to create the filling.

Divide the dough into 4 parts.

Roll each part to a 9-inch circle.

Cut each circle into 12 wedges.

Sprinkle each wedge with 1/2 cup of the filling.

Roll each wedge from the outside edge to the middle part.

Bake on an ungreased cookie sheet at 375 degrees F (190 degrees C) for 20 minutes.