In a large mixing bowl, beat the room-temperature unsalted butter and granulated sugar together using an electric mixer until the mixture is light and fluffy. This should take about 2-3 minutes.
Next, add the lightly beaten egg, pure vanilla extract, and almond extract to the butter mixture. Beat until well combined, ensuring that all ingredients are fully incorporated.
In a separate bowl, whisk together the all-purpose flour and kosher salt until well blended. Gradually add this dry mixture to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix to ensure your cookies remain tender.
Once the dough is ready, divide it into equal portions based on how many colors you want to create. For example, if you want three colors, divide the dough into three parts. Add a few drops of food coloring to each portion, and knead the dough until the color is evenly distributed.
Now comes the fun part! Take small pieces of each colored dough and layer them together. Gently roll them into a log shape. Then, twist and fold the log to create a marbled effect. Roll the log in coarse sanding sugar if desired for an added crunch and sparkle.
Wrap the dough log in plastic wrap and refrigerate for at least 30 minutes. Chilling the dough helps the cookies maintain their shape during baking and enhances the flavors.
Preheat your oven to 350°F (175°C) while the dough chills. Line your baking sheets with parchment paper to prepare for baking.
Once chilled, remove the dough from the refrigerator. Slice the log into equal rounds about ½ inch thick. Place the cookies on the prepared baking sheets, leaving space between them as they will spread slightly.
Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden. Keep an eye on them to prevent over-baking.
Remove the cookies from the oven and let them cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely. Enjoy your beautiful Tie-Dye Cookies (Butter Cookies) with a glass of milk or your favorite beverage!
