Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper if desired.
In a large mixing bowl, beat the granulated sugar, brown sugar, and softened butter together using an electric mixer until creamy.
Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.
In another bowl, whisk together the flour, cocoa powder, baking powder, and salt.
Gradually add the dry ingredients to the wet ingredients and mix until just combined. The dough will be thick and sticky.
Cover the dough and chill in the refrigerator for about 30 minutes (this helps the cookies hold their shape).
Once chilled, use a cookie scoop or tablespoon to portion out the dough. Roll each portion into a ball.
Roll each ball in powdered sugar to coat completely.
Place the coated cookie dough balls on the prepared baking sheets, spaced about 2 inches apart.
Bake in the preheated oven for 10-12 minutes, or until the edges are set but the centers are still soft.
Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a cooling rack to cool completely.