Set oven rack to the middle position. Preheat oven to 325ºF (163ºC).
Line two baking sheets with parchment paper.
Whisk flour, cocoa powder, baking soda, baking powder, and salt together in a medium-sized bowl.
Whisk brown sugar, eggs, and vanilla together in a large bowl.
Microwave chopped unsweetened chocolate and butter in a microwave-safe bowl in 30-second increments, stirring occasionally until the chocolate is melted, heating for about 1 1/2 to 2 minutes.
Whisk the melted chocolate into the egg mixture until combined.
Fold flour mixture into the chocolate mixture until no dry streaks remain.
Let the dough sit at room temperature for 10 minutes. The dough will be thich like fudge and feel sticky. It solidifies more as the dough gets cools but does not roll nicely into balls.
Spread the granulated sugar into a shallow dish.
Spread the powdered sugar into a separate shallow dish.
Scoop 2 tablespoons (1 ounce, 32 grams, #30 scoop) sized rounded dough balls and drop one at a time into the granulated sugar, roll to coat and then form into a ball.
Transfer to the powdered sugar bowl and roll to generously coat. Repeat with the remaining dough.
Evenly space the dough balls on the prepared baking sheets, 11 cookies per sheet pan.
Bake cookies one sheet at a time until puffed up and cracked, and the edges have begun to set but the centers still look soft and raw between the cracks, 12 minutes. Make sure to rotate the pan halfway through baking.
Cool cookies on the sheet pan for 5 minutes, then transfer to a cooling rack. Cool completely before serving.