In a big bowl or stand mixer bowl, cream together 1 cup (2 sticks) unsalted butter and 1 1/4 cups granulated sugar on medium-high speed for a few minutes until the mixture turns pale.
Mix in 1 large egg, 2 tsp almond extract, and 1 tsp vanilla bean paste or vanilla extract on medium speed until well combined. Use a rubber spatula to scrape down the bowl's sides and bottom as necessary.
Add 3 cups of flour, 1 tsp cornstarch, 1 tsp baking powder, and 1 tsp fine salt to the butter mixture, then mix on low speed just until combined. Scrape the bowl's sides and bottom with a rubber spatula to ensure thorough mixing.
The dough will still be quite stiff. Split it into three equal parts (about 10.75 oz or 305g each). Keep one part plain, dye another green, and the third red using gel food coloring. Wrap each piece in plastic wrap. Flatten each into a rectangle roughly 1/3 inch thick to simplify later rolling. Ensure the pieces are roughly the same size for even stacking.
Refrigerate the dough for about 30 minutes, freeze for 10 minutes, or chill overnight. If chilled overnight, let it sit at room temperature for about 5 minutes before rolling to soften slightly.
Set the oven to 350 F / 175 C about 30 minutes before cutting the cookies. Prepare two large baking sheets with silicone mats or parchment paper.
Take the plastic wrap off each dough portion and place it flat on the counter. Roll out the dough on the plastic wrap to minimize mess and make cutting easier.
Roll each chilled dough piece to roughly 7x12 inches. Put a sheet of parchment paper on the counter, then stack the dough pieces on it in this order: green at the bottom, white in the middle, red on top. Gently roll over the stack with a rolling pin to fuse them.
Use a sharp knife to cut off any ragged edges. Slice one of the long sides at a slant so that the red layer is slightly narrower than the green along that edge, which enhances the spiral effect. Start rolling the dough from that edge.
Roll the dough into a long, tight log. Lifting the parchment paper to help roll the dough onto itself makes this easier. After rolling, use your finger to press the green dough over the seam to seal the log.
Spread 1 cup of Christmas sprinkles on a rimmed baking sheet. Roll the dough log in the sprinkles, pressing firmly, until it is completely coated. Nonpareils or jimmies are both suitable.
Using a sharp knife, cut the log into slices about 1/3 inch thick. The dough should still be cold enough to hold its shape while slicing. If the log starts to flatten or lose shape, refrigerate it for 15-30 minutes to firm up. Arrange the cookies on the baking sheets, leaving about 2 inches between them to allow for spreading.
Bake one sheet at a time on the middle rack for 12-14 minutes (the exact time varies with cookie size and thickness). Rotate the pan halfway through for even browning. Watch closely and remove the cookies before the edges color. When uncertain, underbake slightly; they will continue to set on the hot pan. The end pieces often look irregular, so those are perfect for tasting. Allow the cookies to cool on the pan for 15 minutes, then transfer to a wire rack to cool completely.
Once fully cooled, store the cookies in an airtight container at room temperature for up to 5 days.
