Instructions

1. Preheat oven to 350° F.
2. In a medium-sized bowl, combine brownie mix, egg, vegetable oil and milk. Beat until thoroughly mixed.
3. Line a 9×13” pan with parchment paper or a baking mat. Pour brownie mixture over the baking mat and spread evenly. Line up Oreos in rows on top of the brownie layer.
4. For the cookie
5. Soften butter in the microwave 10-15 seconds. Combine butter with both light brown sugar and granulated sugar. Mix until smooth and mixture becomes fluffy.
6. Add egg and vanilla extract and beat until egg is thoroughly incorporated.
7. In a separate bowl, combine flour, salt and baking soda. Slowly add flour mixture to dough batter while mixing at a low speed. Once all the flour has been added, increase speed to medium until dough forms. Add marshmallows and Peppermint M&Ms.
8. Take the cookie dough and flatten in the palms of your hands Drop chunks onto the top of the brownie mixture, gently pressing them down into brownie batter.
9. Bake for 23-25 minutes at 350°F. Remove from oven and allow to cool before cutting. Since I used a baking mat, I was able to completely remove the sheet of brookies from the pan before cutting.