Whisk together the flour, baking powder, and salt in a small bowl. Set aside.

In a large mixing bowl, stir together the ube halaya, granulated sugar, vegetable oil, eggs, and ube extract (if using) until smooth and uniform in color.

Add the flour mixture to the wet ingredients and fold with a rubber spatula until a soft, sticky dough forms with no dry streaks.

Cover the bowl tightly with plastic wrap and refrigerate for at least 2 hours, or overnight, until the dough is firm enough to handle.

Heat the oven to 175 C / 350 F. Line two sheet pans with parchment paper.

Place the powdered sugar in a shallow bowl. Scoop the cold dough into 1.5-inch balls using a cookie scoop.

Roll each ball in powdered sugar until fully coated, then roll a second time so the coating is thick and even.

Place the coated balls 5 cm / 2 inches apart on the prepared sheet pans.

Bake for 11 minutes, until the edges are set and the surface has crinkled and cracked. The centers will look slightly underdone - that's correct.

Let the cookies cool on the sheet pan for 5 minutes, then transfer to a wire rack to cool completely.