In a large bowl, stir together the flour, cocoa powder, salt, baking soda, and baking powder.
In a medium bowl, whisk together the melted butter, eggs, sugar, and brown sugar until well combined. Pour wet ingredients into the dry ingredients and stir together until just combined. Cover dough with plastic wrap and refrigerate for 2 hours.
Preheat oven to 350 degrees F. Line two baking sheets with parchment paper. Place powdered sugar in a small bowl.
Scoop 2 tablespoons of dough and roll into a ball. Roll ball in powdered sugar then place on prepared baking sheet. When all dough is rolled in powdered sugar, roll each piece again in powdered sugar.
Bake for about 14 minutes until cookies puff up and crack. The edges will be set but the cracks will still look moist. Cool completely on baking sheet.