Using an electric mixer, cream together the butter and granulated sugar until light and fluffy (2-3 minutes on medium speed).

Add the powdered sugar, vanilla and flour. Mix on low speed until a stiff dough forms. Cover dough and refrigerate for 1 hour.

Roll the dough out to ~1/2” thickness. Cut cookies into 1”x3” rectangles and place on a parchment-lined sheet pan. Using a small fork, prick the tops of the cookies in several places.

Place sheet pan in the refrigerator for about 30 minutes.

Preheat oven to 325°F.

Bake at 325°F for 26-28 minutes, or until edges of cookies turn light brown. Let cookies cool fully before dipping.

Place the semi-sweet chocolate in a medium heat-proof bowl and set over a pan of simmering water. Stir until the chocolate has fully melted.

Using an offset spatula, spread the melted chocolate onto the end of the cookies. Place on a cooling rack and sprinkle with red and green sanding sugar. Let cookies cool until chocolate has hardened (~20 minutes).

Repeat process with the white chocolate and remaining undipped cookies.