Preheat the oven to 350 F. Line a 12 cup muffin pan with paper liners. In a large bowl, whisk together flour, sugar, cocoa powder, salt, and baking soda. Add in the eggs, melted butter, and vanilla extract until smooth.
In another large bowl, mix together cake mix, eggs, vegetable oil, and peanut butter until smooth. In a shallow dish, combine granulated sugar and ground cinnamon. Evenly divide the brownie batter between the prepared muffin pan.
Roll the cookie dough into balls, and roll each one into the cinnamon sugar mixture. Place the cookies on each brownie cup. Bake for 20-25 minutes.
