Preheat the oven to 350°F.
Stir the brownie mix, water, oil, and 2 eggs together in a medium sized bowl until combined.
Pour the brownie batter into a greased 13×9 inch pan.
Bake the brownies for 30 minutes or until a toothpick inserted in the center comes out clean.
Meanwhile, in a large bowl, beat the cream cheese, butter, and peanut butter until smooth.
Mix in the powdered sugar, brown sugar, flour, and vanilla.
Then gently stir in the oats, chocolate chips, and M&M’s.
Refrigerate the dough for about 30 minutes.
Once the brownies are completely cooled and the dough is chilled, evenly spread the cookie dough on top of the brownies.
Press the dough down gently to adhere to the brownies.
Refrigerate for an hour before cutting.
Cut into small pieces to serve.
Store in the refrigerator.