Preheat your oven to 350°F (177°C) and line two baking sheets with parchment paper.

In a medium mixing bowl, whisk together the dry ingredients: flour, baking powder, baking soda, and salt.

In a large mixing bowl, beat together the unsalted butter and granulated sugar until light and fluffy, about 2-3 minutes.

Add the egg and vanilla extract to the butter-sugar mixture and beat until fully combined.

Gradually add the dry ingredients to the wet mixture, mixing on low speed until just combined.

Take ⅔ of the cookie dough and set it aside, adding ube extract to the remaining dough; mix until purple.

Portion out 50 grams of vanilla dough and 50 grams of ube dough, pressing them together to create marbled balls and rolling in granulated sugar.

Place the cookie balls on the lined baking sheets, spacing them about 2 inches apart and bake for 10-12 minutes.

Let the cookies cool on the baking sheet for 10 minutes before transferring to a cooling rack.