In a large mixing bowl, beat the softened unsalted butter with powdered sugar using an electric mixer on medium speed for about 3 minutes until light and fluffy.

Add the egg, peppermint extract, and vanilla extract to the creamed mixture and beat on low speed until combined.

In a separate bowl, whisk together the all-purpose flour and salt. Gradually add this to the wet ingredients, mixing on low speed until just combined.

Divide the dough in half. Add red gel food coloring to one half and mix until evenly distributed.

Wrap both portions of dough separately in plastic wrap and refrigerate for at least 30 minutes.

Preheat oven to 350°F (175°C) and line baking sheets with parchment paper. Take a tablespoon of red and white dough, roll into ropes, and twist them together.

Arrange the shaped cookies on the baking sheets, spacing them about 2 inches apart and sprinkle with sanding sugar if desired.

Bake for 9-11 minutes, keeping an eye on the cookies to ensure edges are set while centers remain slightly soft.

Let the cookies cool on the baking sheet for about 5 minutes before transferring them to a wire rack.