Cut the butter into the flour and mix until the mixture resemble coarse crumbs. Stir in the sour cream. Cover and refrigerate cough overnight.
Preheat oven to 350 degrees F (175 degrees C).
Bake cookies on a parchment lined baking sheet at 350 degrees F (175 degrees C) for 20 to 25 minutes.
Combine the sugar, chopped nuts and cinnamon.
Divide chilled dough into quarters. On a lightly floured surface roll out dough into circles 1/8 to 1/4 inch thick. Cut into wedges and sprinkle with the nut mixture. Roll up into crescent shapes, starting with the wide end first.
Sprinkle cooled cookies with confectioners' sugar.