01 - Preheat the oven to 350°F (175°C). 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 combined.
03 - In a large bowl using an electric mixer, beat the softened unsalted butter, granulated sugar, and packed light brown sugar on medium speed until light and fluffy, about 2 to 3 minutes.
04 - Beat in the large egg, vanilla extract, and cotton candy flavoring into the butter mixture until fully combined and smooth.
05 - Gradually add the dry ingredient mixture to the wet ingredients, mixing on low speed until just combined. Avoid overmixing.
06 - Divide the dough evenly into two separate bowls. Add pink gel food coloring to one bowl and blue gel food coloring to the other. Fold gently until each portion reaches a soft pastel shade.
07 - Pinch off a small piece of dough from each colored portion and gently press them together to form a swirled ball. Place on the prepared baking sheets, spacing each ball about 2 inches apart. Optionally, roll each dough ball in colored sprinkles before placing on the sheet.
08 - Bake for 9 to 11 minutes, until the edges are just set and the centers still appear slightly underbaked. Remove from the oven promptly.
09 - Allow the cookies to rest on the baking sheets for 5 minutes, then transfer them to a wire cooling rack to cool completely before serving or storing.