Cut butter into flour with pastry cutter or fingertips

Add sour cream, walnuts, and egg yolk

Mix into dough with hands

Wrap in wax paper and plastic wrap and refrigerate overnight 5. Allow dough to come to room temperature

Preheat oven 375 F

Mix the sugar and cinnamon in a small bowl and set aside

Cut into four equal pieces

For each piece, use a rolling pin to create 1/8 inch thick circle

Sprinkle the cinnamon and sugar mixture over the dough

Cut into 12 equal wedges

Roll each wedge and place on lined baking sheet

Bake for about 20 minutes or until lightly browned

Toss in confectioner sugar when cookies are cool to the touch, but still warm.