01 -
Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.
02 -
In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.
03 -
In a large mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until the mixture is light and fluffy, about 3-4 minutes.
04 -
Add the egg, egg yolk, and vanilla extract to the butter mixture and mix until well combined.
05 -
Gradually add the flour mixture to the wet ingredients, blending until just combined. Do not overmix.
06 -
Divide the dough into two equal portions. Add cocoa powder to one half, mixing until evenly incorporated. The other half will remain plain.
07 -
On a lightly floured surface, take a piece of plastic wrap and place one dough half in the center. Shape it into a log and wrap it securely. Repeat with the second dough half. Refrigerate both logs for at least 1 hour or until firm.
08 -
Once the dough is chilled, remove it from the refrigerator and roll each log out into a rectangular shape about 1/4 inch thick.
09 -
Lay the cocoa dough rectangle over the plain dough rectangle. Starting from one end, gently roll the dough tightly into a log.
10 -
Wrap the swirled log in plastic wrap and refrigerate again for 1 hour.
11 -
Remove the log from the refrigerator and cut it into 1/4-inch thick slices. Place the cookies on the prepared baking sheets with a little space between them.
12 -
Bake in the preheated oven for 10-12 minutes or until the edges are lightly golden.
13 -
Allow the cookies to cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.
14 -
Once cool, dust the cookies with powdered sugar and sprinkle with red and green sprinkles to add festive decoration.