Preparing the Dough

1. In a large bowl, cream the softened butter and granulated sugar together until light and fluffy.
2. Add the egg and vanilla extract, mixing until fully combined.
3. In a separate bowl, whisk together flour, baking powder, and salt. Gradually add the dry ingredients to the butter mixture, mixing just until combined. Be careful not to overwork the dough.

Dividing and Coloring the Dough

1. Divide the dough into 4–6 equal portions.
2. Add a few drops of gel food coloring to each portion and mix until fully incorporated, using a separate bowl or spoon for each color.
3. Flatten each colored dough portion into a disc and wrap in plastic wrap. Chill for at least 30 minutes.

Creating the Swirl Effect

1. Take small portions of each colored dough and stack or twist them together to create a swirled pattern.
2. Gently roll the combined dough into a ball and then flatten it slightly into a cookie shape.

Baking the Cookies

1. Preheat your oven to 350°F (175°C).
2. Place the cookies on a parchment-lined baking sheet, spacing them about 2 inches apart.
3. Bake for 8–10 minutes or until the edges are lightly golden. Let the cookies cool on the sheet for a few minutes before transferring them to a wire rack.