In a medium bowl, whisk the dry ingredients - flour, cocoa powder, cornstarch, baking powder, and salt.

In a separate bowl, whisk the wet ingredients - butter, egg white, and vanilla. Stir in the palm sugar.

Add in the flour mixture, stirring until incorporated. Chill the cookie dough for 30 minutes.

Preheat the oven to 350°F, and line a baking sheet with a silicone baking mat or parchment paper.

Roll the cookie dough into small balls, and then roll into chopped pistachio and place them on the prepared baking sheet. Using your index finger or thumb, make an indentation in the center of each. Bake at 350°F for 8-10 minutes. Cool on the baking sheet for 10 minutes before carefully transferring to a wire rack.

For Chocolate center, melt the chocolate chips. Spoon about a tsp into the center of each cookie.