Peanut Butter Mississippi Mudpie Brownies

Peanut Butter Mississippi Mudpie Brownie on a blue napkin

Peanut Butter Mississippi Mudpie Brownies

All the indulgence of Mississippi Mud Pie packed into decadently layered, fudgy brownies with a salty‑crunchy peanut butter twist.

Course Dessert

Cuisine American

Keyword bar, brownie, chocolate, coffee, decadent, espresso, layered, marshmallow, peanut, peanut butter, pecan

Prep Time 1

Cook Time 50

Total Time 1 50

Servings

Calories 255kcal

Equipment

3 small bowls (1 microwave/heat safe)
3 large bowls (1 heat safe)
2 medium saucepans
baking pan (9"x13")
electric mixer (stand mixer preferred)
As an Amazon Associate I earn from qualifying purchases.kitchen scale (or measuring cups)
measuring spoons

Ingredients

Brownies

96 g flour
20 g cocoa powder
1 tsp salt
272 g dark chocolate
180 g unsalted butter
2 tsp espresso powder
160 g sugar
90 g brown sugar
15 ml vanilla
4 eggs room temperature
10 Oreos crushed (java chip or other coffee forward flavor)
170 g chocolate chips semisweet or bittersweet
320 g crunchy peanut butter

Marshmallow Layer

6 g gelatin
180 ml water divided use
1 tbsp vanilla bean paste
213 g sugar
113 g light corn syrup
½ tsp salt
½ tsp espresso powder optional
5 Oreos crushed (java chip or other coffee forward flavor)
56 g pecans toasted and chopped

Fudge Frosting

90 ml milk (1/4 C + 2T)
84 g butter
267 g sugar
24 g cocoa powder
¼ tsp salt
1 tsp vanilla
128 g quality semi-sweet chocolate chips

US Customary - Metric

Instructions

Make the brownies:

Preheat oven to 350° F. Lightly grease, or line with non-stick foil, a 9” x 13” brownie or cake pan.
In a small bowl, whisk together the flour, cocoa powder and salt and set aside.
96 g flour, 20 g cocoa powder, 1 tsp salt
Place the dark chocolate, unsalted butter, and espresso powder in a large microwave safe bowl. Heat in 30 second intervals, stirring after each just until the chocolate is fully melted; set aside.
272 g dark chocolate, 180 g unsalted butter, 2 tsp espresso powder
In a large mixing bowl, whisk together the sugar, brown sugar, vanilla and eggs until thick and syrupy. The sugar should be dissolved, but avoid incorporating too much air or the brownies will become cakey or crumbly.
160 g sugar, 90 g brown sugar, 15 ml vanilla, 4 eggs
Whisk the chocolate mixture into the egg mixture until completely combined, uniform in color, and smooth, thick and glossy.
Stir in the flour mixture just until the dry ingredients disappear. Fold in the crushed Oreos and chocolate chips.
10 Oreos, 170 g chocolate chips
Pour the batter into the prepared pan, smooth out to the edges in an even layer. Place the pan in the pre-heated oven and bake for about 30-35 minutes. The top should look dry and glossy, the edges will be set and slightly puffed. There may be some cracks in the surface.
In a small microwave safe bowl, heat the peanut butter until it is a loose, pourable consistency. Pour the peanut butter over the surface of the baked brownies - use the back of a spoon or an offset spatula to spread the peanut butter until the entire surface is covered.
320 g crunchy peanut butter

Make the marshmallow:

Combine the gelatin, half of the cool water and vanilla bean paste in a small bowl, set aside to allow the gelatin to bloom.
6 g gelatin, 90 ml water, 1 tbsp vanilla bean paste
Heat the remaining water, sugar, corn syrup, salt, and espresso powder (if you are using it) in a medium saucepan until it reaches 250° F. Immediately transfer to a large heat safe mixing bowl and cool to 212°F.
90 ml water, 213 g sugar, 113 g light corn syrup, ½ tsp salt, ½ tsp espresso powder
Add the gelatin and vanilla mixture and beat on high speed until it is very thick, white, and about tripled in volume.
Quickly spoon, pour or pipe the marshmallow over the top of the peanut butter and spread it out to the edges of the pan. Don’t worry if the peanut butter and marshmallow swirl together a bit.
Before the marshmallow can set, evenly distribute the crushed Oreos and toasted pecan pieces over the surface of the marshmallow. Allow the marshmallow to cool completely and set.
5 Oreos, 56 g pecans

Make the fudge frosting:

Combine milk, butter, sugar, cocoa and salt in medium saucepan on the stove. Turn burner on to medium. Heat the mixture, stirring constantly, to bring to a boil.
90 ml milk, 84 g butter, 267 g sugar, 24 g cocoa powder, 1/4 tsp salt
When the mixture hits a rolling boil (a boil that cannot be stirred down), continue cooking and stir constantly for 1 minute (use a timer).
Remove the pan from the heat. Quickly add the vanilla, and chocolate chips.
1 tsp vanilla, 128 g quality semi-sweet chocolate chips
Stir continually with a wooden spoon or silicone spatula until blended and creamy. Watch closely, the boiled icing will go from shiny to flat in color. This means it is cooling and starting to set. Pour the frosting over the marshmallow layer and very quickly spread with spatula. (If the frosting is too hot or the marshmallow has not fully set you may see the marshmallow start to melt and push up through the frosting, don't worry if this happens, the brownies may look a little more rustic, but they will be just as delicious.)
Allow the frosting to set completely before cutting into bars. Chilling the brownies in the refrigerator for about an hour or so can help ensure clean cuts.

Nutrition