Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper.
In a large bowl, mix melted butter, granulated sugar, and brown sugar until well combined.
Add eggs and vanilla extract, and mix until smooth.
In another bowl, whisk together flour, cocoa powder, baking powder, and salt.
Gradually add dry ingredients to the wet ingredients, mixing until just combined.
Fold in chocolate chips.
Drop spoonfuls of dough onto the prepared baking sheet.
Bake for 10-12 minutes, until edges are set but centers are still soft.
Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.