01 -
Preheat the oven to 350°F (177°C) and line a baking sheet with parchment paper or a silicone mat.
02 -
Using a stand mixer fitted with a paddle attachment, beat the softened butter with granulated and brown sugars until light and creamy.
03 -
Add the egg white and vanilla extract to the creamed mixture and mix for 30 seconds until fully combined.
04 -
Add flour, baking soda, baking powder, and salt, mixing just until the flour disappears and a soft dough forms.
05 -
Divide the dough into three equal portions, placing each into a separate bowl. Dye one portion red, one green, and leave the third uncolored.
06 -
Scoop one teaspoon from each colored dough portion and gently press together. Optionally, split each teaspoon into halves and layer randomly for a more intricate marbled effect, then roll gently to combine.
07 -
Place the formed dough balls onto the prepared baking sheet and bake at 350°F (177°C) for 7 minutes.
08 -
Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely. Serve alongside a glass of milk if desired.