Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a mixing bowl, whisk together melted butter, granulated sugar, and brown sugar until well combined.
Add in the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
In a separate bowl, mix together the flour, cocoa powder, salt, and baking powder.
Gradually add the dry ingredients to the wet ingredients, gently folding until just combined. Do not overmix.
If using, fold in the chocolate chips until evenly distributed.
Using a cookie scoop or tablespoon, drop rounded balls of the dough onto the prepared baking sheet, spacing them about 2 inches apart.
Bake in the preheated oven for 10-12 minutes, or until the edges are set but the centers are still slightly soft.
Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.