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 eggs, melted butter, and vanilla extract until smooth.
In a large bowl, combine cake mix with eggs and vegetable oil until smooth. Add in mint extract and green food coloring. Mix until smooth. Fold in the chocolate chips and mint M&Ms.
Evenly divide the brownie batter between the prepared muffin pan. Top with the cookie dough. Bake for 20-25 minutes.