In a stand mixer, cream the softened butter and sugar for 3–4 minutes until light and fluffy.

Add in the egg and vanilla extract and blend well, scraping down the sides as necessary.

In a separate bowl, whisk the all-purpose flour, kosher salt, and baking soda together.

Gradually add the dry mixture to the butter mixture on low speed until just combined.

Divide the dough into three equal portions. Color one portion red, one green, and leave one plain.

Shape into balls, wrap in plastic, and chill for about 1 hour.

Roll each dough ball between parchment paper into 7-inch squares, and chill again for 15 minutes.

Stack the colored layers in order—red, green, and plain—and roll into a 12×8-inch rectangle.

Remove the top parchment, roll the dough lengthwise into a log, and freeze for 1 hour.

Preheat your oven to 350°F (175°C) and line baking sheets with parchment paper.

Slice the dough log into ⅓-inch cookies and roll the edges in red sanding sugar.

Bake the cookies on prepared sheets for 8–10 minutes until set and slightly golden.

Cool on the baking sheet for 1 minute before transferring to a wire rack.

Store in an airtight container to keep fresh and delicious.