Koulourakia (greek butter twist) recipe in the greek category

: Cream butter and shortening in a large mixing bowl. Gradually add sugar, beating well at medium speed of electric mixer. Add eggs, one at a time, beating well after each addition. Add vanilla extract. Beat until blended. Combine flour, baking powder and baking soda. Gradually add to creamed mixture, mixing after each addition. Chill dough 1 to 2 hours. Divide dough into fourths. Divide each fourth into 16 portions. Roll each portion into a 4-inch rope. Fold each rope in half, and twist. Place twists 2 inches apart on greased baking sheets. Combine egg yolk and water. Brush over twists. Sprinkle lightly with cinnamon and sesame seeds. Bake at 325 degrees F for 20 to 25 minutes or until light golden brown. Immediately transfer to wire racks to cool.