Preheat your oven to 350° and line a couple baking sheets with parchment paper or a silicone baking mat.
In a large mixing bowl combine your softened butter and your sugars and mix using a hand or stand mixer.
Mix in your peanut butter and then your egg and vanilla.
Then mix in your flour, cocoa powder, baking soda, and salt.
Form your dough into golf sized balls and place on your lined baking sheet.
Use a fork to press a crisscross indent onto the top of your cookies (this will flatten them about halfway).
Bake your cookies for 11-13 minutes.