In a large bowl or stand mixer, beat the unsalted butter and granulated sugar on medium-high speed for a couple of minutes until lightened in color.

Mix in the large egg, almond extract, and vanilla extract or vanilla bean paste on medium speed until fully combined, scraping the bowl as needed.

At low speed, add all-purpose flour, cornstarch, baking powder, and salt to the butter mixture just until combined, scraping the sides and bottom.

Divide the dough into three equal parts (~10 oz or 305g each). Leave one portion plain, color one with red gel food coloring, and the other with green gel food coloring. Flatten each into rectangles about 1/3 inch thick and wrap in plastic wrap.

Refrigerate wrapped dough portions for 30 minutes, freeze for 10 minutes, or chill overnight. If chilled overnight, let sit at room temperature for 5 minutes before rolling.

Preheat the oven to 350°F (175°C) 30 minutes before baking. Line two large baking sheets with silicone mats or parchment paper.

Remove dough from plastic wrap and roll each portion into approximately 7x12-inch rectangles on the plastic wrap.

Place parchment paper on the counter and layer dough with green on the bottom, plain in the middle, and red on top. Gently roll them together, trim uneven edges, and cut a diagonal on one long side.

Roll the layered dough from the cut edge into a tight spiral log, using the parchment to assist. Press the seam gently to seal the log.

Pour Christmas sprinkles on a rimmed tray and roll or press the cookie log in sprinkles until fully coated.

Using a sharp knife, cut cookies about 1/3 inch thick while the dough is still cold. If the log softens, chill for 15-30 minutes. Place cookies on prepared sheets spaced 1 inch apart.

Bake one sheet at a time on the middle oven rack for 12-14 minutes, rotating halfway. Remove when edges just start to color.

Let cookies cool on the baking sheet for 15 minutes, then transfer to a wire rack to cool completely before storing.

Store the baked cookies in an airtight container at room temperature for up to 5 days.