Combine flour, baking powder, and salt in a small bowl and whisk.

Cream butter, light brown sugar, and 1/2 cup granulated sugar until light and fluffy using a mixer with a paddle attachment.

Add egg and beat until well combined.

Incorporate mashed ube (purple sweet potato), ube flavoring, and purple food coloring to achieve desired color.

Gradually add dry ingredients and mix on low speed until just combined.

Form the dough into a disc, wrap it in plastic, and refrigerate for at least 2 hours or overnight.

Preheat oven to 350 degrees F (175 degrees C).

Using a 2 tablespoon scoop, form dough into balls and roll them in the remaining granulated sugar.

Place cookies on a baking sheet, 12 per tray.

Bake for 14-16 minutes, or until just set.

Transfer cookies to a wire rack to cool completely.

Insert white chocolate chips, point side down, into the cookies to form eyes.

Add a small drop of melted dark chocolate to the center of the white chocolate chips to create pupils.