These Peanut Butter Marshmallow Brownies are a chocolate lover’s dream come true, layering a fudgy brownie base with salty peanut butter and gooey marshmallows. This recipe is the ultimate decadent treat for potlucks, bake sales, or a special family dessert.
Imagine a rich, cocoa-infused brownie smothered in melted crunchy peanut butter, topped with pillowy toasted marshmallows and finished with a warm, glossy chocolate frosting.
Recipe Details
- Flavor Profile: A nostalgic and rich combination of deep chocolate, salty roasted peanuts, and sweet vanilla marshmallows.
- Textures: Fudgy and dense at the bottom, crunchy and creamy in the middle, and topped with a light, fluffy marshmallow layer and a smooth, fudge-like frosting.
- Total Time: Approximately 10 minutes of prep, 17–20 minutes for the base bake, and an additional 3–5 minutes for the marshmallow topping.
- Difficulty: Easy to moderate. While there are several layers, each step is straightforward and uses common pantry staples.
What You’ll Need
To create these layered bars, you will start with a simple brownie base made from melted butter, cocoa, and flour. The magic happens in the toppings, which require a jar of peanut butter, a bag of mini marshmallows, and a quick homemade chocolate frosting. The frosting is a traditional cooked-style glaze that becomes beautifully glossy once beaten.
Ingredient Notes
- Salted Butter – Melting the butter for the base ensures a dense, fudgy texture rather than a cakey one.
- Cocoa Powder – Used in both the brownie batter and the frosting for a double dose of chocolate.
- Peanut Butter – Using a crunchy variety provides a fantastic texture contrast against the soft marshmallows and fudgy base.
- Mini Marshmallows – These melt quickly and evenly, creating a consistent layer across the top of the brownies.
- Chocolate Chips – Sprinkled onto the batter before baking, these create extra pockets of melted chocolate throughout the base.
- Powdered Sugar – The foundation of the glossy frosting that sets up perfectly over the warm marshmallow layer.
Add-ins and Substitutions
- Nut Variations: If you prefer a smoother texture, you can substitute the crunchy peanut butter for creamy, though the crunch is highly recommended.
- Extra Chocolate: You can use dark chocolate chips instead of semi-sweet if you prefer a less sweet, more intense chocolate flavor.
- Salty Finish: A tiny pinch of flaky sea salt on top of the finished frosting can help balance the sweetness of the marshmallows.
How to Make Peanut Butter Marshmallow Brownies
This recipe follows a specific sequence of baking and layering to ensure each component stays distinct while melding together into the perfect bite.
- Prepare the Base: Preheat your oven to 350 F and prepare your 8×8 pan. Whisk together the melted butter, sugar, eggs, and vanilla until the mixture is light and fluffy.
- Incorporate Dry Ingredients: Whisk the salt, flour, and cocoa powder together before stirring them into the wet batter until just combined. Spread this into your pan and top with chocolate chips.
- Initial Bake: Bake the brownies for 17 to 20 minutes.
- Add the Toppings: As soon as they are out of the oven, microwave the peanut butter for 15 seconds until pourable. Spread it over the hot brownies, cover with mini marshmallows, and return to the oven for 3 to 5 minutes until the marshmallows are puffy.
- Whisk the Frosting: While the brownies begin to cool, melt the butter, cocoa, and milk in the microwave until hot. Combine this with powdered sugar and salt in a bowl, beating until the mixture is smooth and glossy. Stir in the vanilla.
- Finish and Set: Pour the warm frosting over the marshmallows. You must allow the brownies to cool completely so the layers can set before you attempt to cut them.
Pro Tip: To get the cleanest slices, let the brownies set at room temperature until the frosting is no longer tacky, then use a warm, dry knife to cut through the layers in one smooth motion.
Recipe Tips
- Don’t Overbake the Base: Pull the brownies out as soon as they are set. They will spend a few more minutes in the oven once the marshmallows are added, and overbaking will result in a dry base.
- Melt the Peanut Butter: Warming the peanut butter is a crucial step; it allows you to spread it easily over the delicate, hot brownie surface without tearing it.
- Glossy Frosting Secret: Be sure the butter mixture is hot enough to fully dissolve the cocoa powder before adding the powdered sugar. Beating it well is what creates that beautiful professional sheen.
- Patience is Key: It is tempting to cut these while warm, but the marshmallows and frosting need time to firm up to create those beautiful distinct layers.
FAQs
Can I use a larger pan for this recipe? This recipe is specifically designed for an 8×8 pan to ensure the brownies have the proper thickness to support the heavy peanut butter and marshmallow layers.
How do I store these brownies? Store them in an airtight container at room temperature for up to 3 days. Because of the marshmallow and frosting layers, stacking them is not recommended unless you place parchment paper between the layers.
Can I make these without a microwave? Yes, you can melt the butter and cocoa for the frosting in a small saucepan over low heat on the stove, and warm the peanut butter in a similar fashion.
Serving Suggestions
- Cold Milk: These are very rich and sweet, making a glass of cold milk the perfect accompaniment.
- Coffee: The bitterness of black coffee provides a great balance to the salty-sweet profile of the peanut butter and marshmallows.
- Ice Cream: Serve a square with a scoop of vanilla bean ice cream for an over-the-top dessert platter.
Make This Recipe in Advance
You can bake the brownie base and add the peanut butter and marshmallow layers several hours before you plan to serve. The frosting is best made and poured while warm, but the entire dessert actually benefits from sitting for a few hours to set up, making it an excellent make-ahead treat.
Print
Peanut Butter Marshmallow Brownies
- Total Time: 35 minutes
- Yield: 16 servings 1x
- Diet: Vegetarian
Description
These Peanut Butter Marshmallow Brownies are a chocolate lover’s dream come true, layering a fudgy, cocoa-infused brownie base with crunchy peanut butter and gooey marshmallows. This 30-minute decadent treat is finished with a warm, glossy chocolate frosting that sets into a professional sheen. Perfect for potlucks or family desserts, these bars offer the ultimate salty-sweet balance in every rich, layered bite.
Ingredients
For the Brownie Base
- 1/2 cup salted butter, melted
- 1 cup granulated sugar
- 2 large eggs, room temperature
- 1 teaspoon vanilla
- 1/2 teaspoon salt
- 3 tablespoons cocoa powder
- 3/4 cup all-purpose flour
- 1/4 cup chocolate chips
For the Toppings
- 1/2 cup peanut butter (crunchy recommended)
- 2 cups mini marshmallows
For the Chocolate Frosting
- 1/4 cup butter
- 2 tablespoons cocoa powder
- 1/4 cup milk
- 2 cups powdered sugar
- 1/4 teaspoon salt
- 1/2 teaspoon vanilla
Instructions
Step 1: Prepare the Base
Preheat your oven to 350°F and grease an 8×8 inch baking pan. In a large bowl, whisk together the melted butter, granulated sugar, eggs, and 1 teaspoon of vanilla until the mixture is light and fluffy.
Step 2: Incorporate Dry Ingredients
Whisk together the salt, flour, and 3 tablespoons of cocoa powder. Gently stir the dry ingredients into the wet batter until just combined. Spread the batter into the prepared pan and sprinkle the chocolate chips evenly over the top.
Step 3: Initial Bake
Bake the brownie base for 17 to 20 minutes until the edges are set but the center remains slightly fudgy.
Step 4: Add the Toppings
Immediately after removing from the oven, microwave the peanut butter for 15 seconds until pourable. Spread it over the hot brownies. Top with an even layer of mini marshmallows and return to the oven for 3 to 5 minutes until the marshmallows are puffy and soft.
Step 5: Whisk the Frosting
While the brownies are in for their final minutes, melt 1/4 cup of butter with 2 tablespoons of cocoa powder and the milk in the microwave (or saucepan) until hot. In a separate bowl, combine this hot mixture with the powdered sugar and 1/4 teaspoon of salt. Beat until smooth and glossy, then stir in 1/2 teaspoon of vanilla.
Step 6: Finish and Set
Pour the warm frosting over the marshmallow layer, spreading it to the edges. Allow the brownies to cool completely at room temperature to let the layers set firmly before slicing.
Notes
Storage Instructions: Store in an airtight container at room temperature for up to 3 days. To prevent the marshmallow and frosting layers from sticking, avoid stacking the brownies unless you place a sheet of parchment paper between each layer.
The ‘Glossy’ Secret: For that professional bakery sheen, ensure your butter and milk mixture is hot when it hits the powdered sugar. Beating the frosting vigorously for a minute after mixing will also enhance the shine.
Cutting Tip: To achieve clean, distinct layers, wait until the frosting is no longer tacky to the touch. Use a sharp, dry knife dipped in warm water and wiped clean between every slice.
- Prep Time: 10 minutes
- Cook Time: 25 minutes
- Category: Dessert
- Method: Baking
- Cuisine: American
Nutrition
- Serving Size: 1 brownie
- Calories: 310
- Sugar: 38g
- Sodium: 225mg
- Fat: 14g
- Saturated Fat: 8g
- Unsaturated Fat: 6g
- Trans Fat: 0g
- Carbohydrates: 46g
- Fiber: 1g
- Protein: 3g
- Cholesterol: 45mg
Keywords: peanut butter marshmallow brownies, layered brownie bars, crunchy peanut butter dessert, marshmallow fudge brownies, easy bake sale recipes
