Combine the flour, baking powder, and salt in a medium bowl. Stir with a whisk to combine.
Add the butter and sugars to a stand mixer with the paddle attachment, and beat until smooth. Scrape down the sides of the bowl as needed.
Melt the chocolate slowly in the microwave (in 20 second intervals) and then drizzle the cooled chocolate into the butter-sugar mixture. Mix until combined.
Add the egg and mix well to combine.
Add the flour mixture to the cookie dough and beat on low speed until combined.
Wrap the crinkle cookie dough in plastic wrap and chill it for about an hour.
Preheat your oven to 325-F, and line 2 baking sheets with parchment paper.
Pour the white granulated sugar into one shallow dish, and the powdered sugar into a second dish.
Scoop 1.5 tablespoons balls of dough and roll them between your hands to make balls. Then, roll the ball in the granulated sugar to coat them evenly. Then, roll the ball in the powdered sugar, then set it aside. Repeat until all the balls have been rolled in powdered sugar.
Roll the balls a final time in the powdered sugar, pressing them down gently to ensure a good, thick coating of sugar. This will create the crinkle effect.
Bake the cookies balls about 2-inches apart for about 16-18 minutes until the cookies are crinkled and set but not browned on the bottom.
Cool on the cookie sheet for 10 minutes then transfer the cookies to a cooling wrack until fully cooled. Enjoy!