Combine flour, baking powder and salt in a small mixing bowl. Whisk to combine.
In mixer fitted with paddle attachment, cream butter, light brown sugar, and 1/2 cup granulated sugar on medium speed until light and fluffy. Add egg and beat until well combined. Add mashed ube or ube jam, ube flavoring and food coloring to reach desired hue.
Add dry ingredients and mix on low speed until just combined.
Form dough into a disc and wrap well with plastic wrap. Refrigerate at least 2 hours or overnight.
Preheat oven to 350 degrees F. Using 2 tablespoon scoop, form dough into balls and roll in remaining granulated sugar. Bake cookies, 12 per tray, 14-16 minutes until just set. Transfer to wire rack to cool completely.
Insert white chocolate chips, point side down, into cookies to form eyes and finish with a drop of melted dark chocolate to form pupils.