Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper.

In a medium bowl, whisk together flour, cocoa powder, baking powder, and salt.

In a separate large bowl, beat granulated sugar, brown sugar, and eggs until light and fluffy. Add vanilla extract and mix to combine.

Gradually add the dry ingredients to the wet, mixing until just combined.

Cover the dough and refrigerate for 30 minutes.

In a small bowl, mix cinnamon and sugar for coating.

Roll chilled dough into balls and coat each in the cinnamon sugar.

Place balls 2 inches apart on the prepared baking sheet.

Bake for 10–12 minutes, or until the cookies have spread and crinkled.

Let cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.