Step 1

Place 1 stick unsalted butter in the bowl of a stand mixer (or a large bowl if mixing by hand or with an electric hand mixer) and let sit at room temperature until softened.

Step 2

Place 1 3/4 cups all-purpose flour, 1 teaspoon baking powder, and 1/4 teaspoon kosher salt in a medium bowl and whisk to combine.

Step 3

Add 1 cup granulated sugar to the butter. Beat with the paddle attachment on medium-high speed until light, fluffy, and doubled in volume, 3 to 5 minutes. Add 1 large egg and beat on low speed until just combined. Use a rubber spatula to scrape down the paddle and sides of the bowl.

Step 4

Add 1/2 cup ube halaya jam, 1 teaspoon liquid purple food coloring, 1 teaspoon ube extract, and 1/2 teaspoon vanilla extract. Beat on low speed until combined and completely purple, 1 to 2 minutes.

Step 5

With the mixer on low speed, gradually add the flour mixture and beat until just combined. Scrape down the paddle and sides of the bowl once more, and beat on low for 30 seconds more.

Step 6

Cover and refrigerate the dough for 1 hour.

Step 7

Arrange a rack in the middle of the oven and heat the oven to 350°F. Line 2 baking sheets with parchment paper.

Step 8

Place 1 cup powdered sugar in a medium, shallow bowl. Divide the dough into 16 portions (about 3 scant tablespoons each), then roll each portion into a smooth ball. Toss the cookie dough balls one at a time in the powdered sugar until completely and generously coated (aim for a layer so thick you can’t see the cookie dough anymore). Place 8 on each baking sheet, spacing them at least 3 inches apart.

Step 9

Bake one sheet at a time until the edges are set but the centers are still soft, 12 to 15 minutes. Let the cookies cool completely on the baking sheet.