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Peanut Butter Mississippi Mud Brownies on a cutting board.
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5 from 1 vote

Peanut Butter Mississippi Mud Brownies

Peanut Butter Mississippi Mud Brownies have a layer of peanut butter, marshmallows, and a rich chocolate icing.
Course Dessert
Cuisine Southern
Keyword brownies, peanut butter
Prep Time 10 minutes
Cook Time 32 minutes
Total Time 42 minutes
Servings 16
Calories 514kcal


  • 4 ounces unsweetened chocolate
  • 2 cups sugar
  • 1 cup butter, softened
  • 4 eggs
  • 1 cup flour
  • 1 teaspoon vanilla extract
  • 2/3 cup semisweet chocolate chips
  • 3 cups mini marshmallows
  • ¾ cup peanut butter
  • 1 teaspoon canola oil
  • ¼ cup butter
  • 3 tablespoons unsweetened cocoa
  • ¼ cup milk
  • 2 cups confectioners' sugar
  • ½ teaspoon vanilla extract


  • Preheat oven to 350°. Chop the chocolate into small pieces, place in a small heavy-bottomed pan and heat over low heat, stirring constantly, until melted. Remove from heat.
  • Using an electric mixer, beat butter and 2 cups sugar at medium speed until light and fluffy. Add eggs one at a time, waiting until each egg is blended in before adding the next one.
  • Add melted chocolate, and beat just until blended. Add flour and 1 teaspoon vanilla extract and beat on low speed until flour is moistened.
  • Spread batter into 9X13-inch pan. Sprinkle semi-sweet chocolate chips on top and bake for 30 minutes if using a metal pan and slightly longer in a glass pyrex dish.
  • Sprinkle marshmallows on top of brownies and return to oven on top rack for 1-2 minutes or until marshmallows are melted and lightly browned on top.
  • Combine peanut butter and canola oil in a small bowl and microwave for 10 seconds on HIGH. Stir to combine and drizzle on top of marshmallow covered brownies.
  • For chocolate frosting, combine ¼ butter, unsweetened cocoa, and milk in a saucepan and cook over medium heat, stirring constantly for 2-3 minutes.. Whisk in powdered sugar and vanilla extract until smooth. Drizzle on top of brownies.


Calories: 514kcal