This recipe for Small Batch Mississippi Mud Bars is unusual because it’s made in an 8 inch square pan. If you’re baking for a group you may want to go for a larger yield recipe, but at our house an 8 inch pan is all we need.
The recipe is originally from an old book called Cookies by the Dozen, but over the years I’ve adjusted it to suit our tastes. The original version was too sweet and more like a messy cake, while this version is still rich, but not quite as sweet. The bottom layer is a cake-y but dense brownie. The brownie is topped with peanut butter, marshmallows and nuts, and the whole thing is topped with a poured on chocolate icing.
For some this is may be a serve-out-of the pan dessert. If your family enjoys digging into melt-y, brownies, then you should probably just bake, cool and serve. However, if you want to brownies to have a cleaner look or if you plan to plate them and serve them with something else, I recommend baking, freezing, cutting while frozen, and then bringing to room temperature. Here’s what the brownies look like right before they go in the freezer.
And then here’s how I usually cut them. The best part is trimming the edges!
Technically you could cut these into 16 squares because they are so rich, but in reality by the time you trim the edges and pick the neatest squares, you’ll probably serve more like 8 to 12. Also, the one in this last photo was actually made with whole milk rather than evaporated, thus the icing is runny. Stick with evaporated for best results.
Small Batch Mississippi Mud Bars
- 1/2 cup 1 stick unsalted butter, softened (114 grams)
- 4 tablespoons unsweetened cocoa powder 20 grams
- 3/4 cup granulated sugar 150 grams
- 3/4 teaspoon vanilla extract
- 2 eggs
- 1/4 teaspoon salt if using salted butter, use only a pinch
- 3/4 cup unbleached all-purpose flour 94 grams
- 1/3 cup semisweet or bittersweet chocolate chips
- 1/2 cup peanut butter
- 1 1/2 teaspoons vegetable oil or coconut oil
- 1-2 cups miniature marshmallows
- 1/2 cup chopped toasted pecan pieces or use more chocolate chips or peanuts
- 1 1/3 cups stirred confectioners' sugar 130 grams
- 1/8 teaspoon salt
- 3 tablespoons unsalted butter 42 grams
- 3 tablespoons natural unsweetened cocoa powder 15 grams
- 3 tablespoons evaporated milk plus more if needed
- 3/4 teaspoon vanilla extract
- Preheat oven to 350 degrees F. Line an 8 inch square pan with nonstick foil or parchment paper.
- In a large saucepan, melt the butter over medium low heat. Add the cocoa powder and stir until smooth, then remove from heat and stir in the sugar and vanilla. Stir in eggs one at a time, then stir in the salt. Add the flour and stir until fully blended.
- Spread batter across bottom of prepared pan and sprinkle with chocolate chips. Bake for about 22 minutes.
- Meanwhile, combine peanut butter and oil in a microwave-safe measuring cup. About a minute before the brownie layer is done, microwave the peanut butter mixture on high for about 20 seconds to soften.
- Pour peanut butter over brownie, then Sprinkle marshmallows on top. Return to oven to bake for 3 more minutes or until marshmallows puff. Sprinkle puffed marshmallows with more chocolate chips and nuts.
- Weigh out confectioners sugar, then sift confectioners sugar into a large bowl. Add salt. Have the bowl of sugar and hand-held mixer ready to go.
- In a small saucepan, melt butter over medium heat just until it starts to melt. Stir in cocoa powder and milk and heat just until mixture begins to boil. Scrape hot mixture into sugar, along with the vanilla. Beat with the hand held electric mixer until smooth, then pour over the marshmallows, working fairly quickly so that the icing doesn't set. Tilt the pan to get the chocolate mixture to cover the marshmallows.
- Let cool completely (this will take several hours), then cover top loosely with plastic and freeze just until firm. Lift the whole cake out and wrap, remove foil and wrap tightly in plastic wrap. Keep frozen until about an hour before you are ready to serve it. Place the frozen cake on a cutting board. Using a Chef's Knife, cut into neat squares. Plate the squares and allow them to come to room temperature.