01 -
Preheat the oven to 350°F (177°C). Line a baking sheet with parchment paper or a silicone baking mat and set aside.
02 -
In a stand mixer fitted with a paddle attachment, beat the softened butter with granulated and brown sugars until light and creamy, about 2-3 minutes.
03 -
Add the egg white and vanilla extract to the creamed mixture and continue mixing for 30 seconds until fully incorporated.
04 -
Sift together the flour, baking soda, baking powder, and salt. Gradually add this to the wet ingredients, mixing just until the flour disappears and a soft dough forms.
05 -
Divide the dough evenly into three portions. Leave one plain, tint one with red gel food coloring, and one with green gel food coloring. Mix each color until uniformly distributed.
06 -
Scoop one teaspoon from each colored dough bowl. Either gently press the three pieces together and roll into balls for a simple marbled pattern or split each teaspoon in half and randomly layer to create a more intricate design, then roll gently into balls.
07 -
Place dough balls on the prepared baking sheet. Roll each lightly in the granulated sugar reserved for rolling. Bake in the preheated oven for 7 minutes.
08 -
Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.