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Mississippi Mud Brownies

Mississippi Mud Brownies

  • Author: Regan at This Baking Life
  • Total Time: 45 minutes
  • Yield: 16 servings


This Mississippi Mud Brownie recipe is AMAZING! Your whole family will love these.


  • 2 large eggs
  • 1/2 cup (4 oz.) melted butter
  • 2 tablespoons tap water
  • 1 (18-oz.) double chocolate premium brownie mix box (I used ALDI Specially Selected)
  • 1/2 (10-oz.) pkg. miniature marshmallows (about 2 1/4 cups)
  • 1 (4-oz.) semi-sweet chocolate baking bar, broken into squares or 4 oz. semi-sweet chocolate chips
  • 1/2 cup half and half
  • 1/2 cup powdered sugar, plus more to taste


  1. Preheat oven to 350 degrees F. Line a square baking pan or dish with parchment paper leaving a 1-inch overhang on 2 sides of pan.
  2. Stir together brownie mix, eggs, butter, and water in a medium bowl until smooth. Pour brownie batter into prepared pan, spreading to edges.
  3. Bake, uncovered, until a wooden pick inserted in center comes out with a few moist crumbs, 33 to 35 minutes. (Cook times may vary depending on brand of brownie mix.)
  4. During last 5 minutes of cook time for brownies, place chocolate and 1/2 cup half-and-half in a microwave-safe bowl; microwave on HIGH in 15-second intervals, stirring after each interval (be careful not to overcook or chocolate will seize) until chocolate is melted, 45 to 60 seconds total. (Mixture will not be smooth at this point.)
  5. Whisk in 1/2 cup powdered sugar, whisking until smooth and glossy. Add additional powdered sugar, 1 tablespoon at a time, as needed to sweeten chocolate mixture. 
  6. Remove from brownies from oven. Pour about half of chocolate mixture over hot brownies and carefully smooth out evenly over top of brownies. Top evenly with mini marshmallows, and spoon remaining chocolate mixture over marshmallows.
  7. Place brownies on a wire rack, and let stand at room temperature until completely cool, about 2 hours. (Place brownies in refrigerator for 1 hour for easier cutting.)
  8. Using parchment paper overhang, lift cooled brownies from pan, and cut into squares using a sharp knife. Store in an airtight container or wrap tightly in plastic wrap.


If preferred, you can substitute 1 cup of storebought chocolate frosting or chocolate icing (heated in microwave) for the homemade chocolate sauce.

I prefer to make any type of bar cookie or squares using this parchment paper-lined dish method. It makes them easier to lift from the pan and cut cleanly. If preferred, you can use aluminum foil in place of the parchment paper. Or you can skip the lining step altogether and coat the pan or dish with baking spray or cooking spray.

  • Prep Time: 10 min
  • Cook Time: 35
  • Category: Dessert
  • Method: Baking
  • Cuisine: American


  • Serving Size: 1 brownie
  • Calories: 300
  • Sugar: 27 g
  • Sodium: 180 mg
  • Fat: 17 g
  • Carbohydrates: 40 g
  • Fiber: 2 g
  • Protein: 3 g

Keywords: mississippi mud brownies