Ooey Gooey Mississippi Mud Brookies. These layers bars are filled with chocolate chips, pecan and mini marshmallows. You have to decide which layer you like better, the gooey chocolate brownie or the chewy chocolate chip cookie.

Gooey Mississippi Mud Brookies

  • Author: Julianne Dell
  • Prep Time: 15 mins
  • Cook Time: 25 mins
  • Total Time: 40 minutes
  • Yield: 12-15 slices


These Gooey Mississippi Mud Pie Brookies are layers of fudge chocolate brownie and chocolate chip cookies mixed with pecans and mini marshmallows.


For the Brownies:

  • 1 Box brownie mix
  • Ingredients on the box (oil, eggs water)
  • 1 ½ cups mini marshmallows, divided
  • 1 cup chopped pecans, divided

For the Cookie Dough:

  • ½ cup (1 stick) unsalted butter
  • ½ cup light brown sugar, packed
  • ½ cup granulated sugar
  • 1 Large egg
  • 2 teaspoons pure vanilla extract
  • 1¾ cup all-purpose flour
  • ½ teaspoon salt
  • ½ teaspoon baking soda
  • ¾ cup mini chocolate chips


  1. Preheat oven to 350°F
  2. In a medium sized bowl, combine brownie mix, egg, vegetable oil and water according to the instructions on the box. Beat until thoroughly mixed.
  3. Line a 9×13” pan with parchment paper or a baking mat. Pour the brownie batter over the baking mat and spread evenly.
  4. Sprinkle the top of the batter with ½ cup crushed pecans and ¾ cup of mini marshmallows and gently press into the brownie batter.
  5. Soften the butter in the microwave for 10-15 seconds. Combine the butter with both light brown sugar and granulated sugar. Mix until smooth and the mixture becomes fluffy.
  6. Add the egg and vanilla extract and beat until the egg is thoroughly incorporated.
  7. In a separate bowl, combine the flour, salt and baking soda. Slowly add the 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 chocolate chips, remaining pecans and marshmallows last and fold into cookie dough.
  8. Take the cookie dough and drop chunks onto the top of the brownie mixture, gently pressing them down into brownie batter. Do you best to cover evenly.
  9. Bake for 25-28 minutes at 350°F. Remove from oven and allow to cool completely before cutting. Since I used a baking mat, I was able to completely remove the sheet of brookies from the pan before cutting. If the brownie is still too gooey, I suggest refrigerating before cutting.
  • Category: Dessert
  • Method: Baked
  • Cuisine: American