- Grease a mug with butter. Set aside. In a separate mixing bowl, whisk together the flour, unsweetened cocoa powder, granulated sugar, baking powder, and salt until well combined. Add the milk, oil, and pure vanilla extract and continue mixing until fully combined. Pour the batter into the prepared mug and sprinkle the chocolate chips on top. Transfer the mug with the batter to the microwave and microwave for 60-90 seconds. Carefully remove from the microwave and allow to cool slightly, serve.