01 - Preheat the oven to 350°F. Line two baking sheets with parchment paper and set aside.
02 - In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt until evenly distributed. Set aside.
03 - In a large bowl, use an electric mixer to beat the softened butter, granulated sugar, and brown sugar on medium speed until pale, light, and fluffy, about 2 to 3 minutes.
04 - Add the eggs one at a time, mixing well after each addition. Blend in the vanilla extract and cotton candy flavoring until the mixture is smooth and fully combined.
05 - Gradually add the dry ingredient mixture to the wet ingredients, mixing on low speed until a soft, cohesive dough forms. Avoid overmixing.
06 - Divide the dough evenly into two separate bowls. Add a few drops of pink gel food coloring to one half and blue gel food coloring to the other, kneading each until the color is uniform throughout.
07 - Pinch off a small portion of each colored dough and gently press and swirl them together in your palms to form a 1.5-inch ball with a marbled appearance. Arrange on the prepared baking sheets, spacing them about 2 inches apart.
08 - Bake for 9 to 11 minutes, or until the edges are set but the centers still feel slightly soft. Avoid overbaking to maintain a chewy texture.
09 - Let the cookies rest on the baking sheets for 5 minutes to firm up, then carefully transfer them to a wire rack to cool completely.
10 - If desired, top each cooled cookie with a small tuft of cotton candy just before serving. Add the garnish at the last moment, as cotton candy dissolves quickly when exposed to moisture.