Get ready to meet your new favorite dessert. These Marshmallow Peanut Butter Brownie Bars are a triple-decker delight, layering a rich, fudgy brownie base with a gooey marshmallow center and a creamy peanut butter topping. Every bite is an unforgettable explosion of chocolate and peanut butter, with a wonderfully soft texture that will have you reaching for seconds. This recipe is surprisingly easy to make and is the perfect treat for parties, potlucks, or a simple Tuesday night indulgence.
Why These Marshmallow Peanut Butter Brownie Bars Are a Must-Try
You’re going to absolutely love this recipe, and here’s why. It’s the perfect balance of rich flavors and textures. The deep, dark chocolate brownie provides the perfect fudgy foundation, cutting through the sweetness of the fluffy marshmallow layer. The peanut butter swirl on top adds a creamy, salty contrast that ties everything together. Plus, these bars look just as amazing as they taste, making them a show-stopping dessert for any occasion. They’re a step above your average brownie but just as simple to bake.
These bars are easy to make and perfect for a crowd.
Key Ingredients You’ll Need
This recipe uses simple, staple ingredients to create its three distinct and delicious layers. Here’s what you’ll need to have on hand.
For the Fudgy Brownie Layer:
Unsalted Butter: Melted butter is the key to a fudgy, dense brownie texture rather than a cakey one.
Granulated Sugar: Provides sweetness and contributes to that classic crackly brownie top.
Eggs: Act as a binder and add richness and moisture.
Vanilla Extract: Enhances the deep chocolate flavor.
All-Purpose Flour: Gives the brownies structure. Be careful not to overmeasure!
Unsweetened Cocoa Powder: Use a quality brand for the richest, most intense chocolate taste.
Salt: Balances the sweetness and brings out the chocolate notes.
For the Gooey Marshmallow Center:
Miniature Marshmallows: These melt beautifully into a perfectly gooey, stretchy layer.
For the Rich Peanut Butter Topping:
Creamy Peanut Butter: Provides the signature nutty flavor. Standard creamy peanut butter works best; avoid natural varieties that can separate.
Powdered Sugar: Helps thicken the peanut butter so it sets properly.
Melted Butter: Makes the peanut butter layer smooth and spreadable.
Step-by-Step Instructions
Follow these simple steps to assemble your incredible layered brownie bars.
Prep Your Pan: Preheat your oven to 350°F (175°C). Grease an 8×8 inch baking pan and line it with parchment paper, leaving an overhang on the sides to use as handles later.
Make the Brownie Batter: In a large bowl, whisk together the melted butter and granulated sugar until well combined. Beat in the eggs one at a time, followed by the vanilla extract. In a separate bowl, whisk together the all-purpose flour, cocoa powder, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix.
Bake the Brownie Layer: Pour the batter into your prepared pan and spread it into an even layer. Bake for 20-25 minutes, or until a toothpick inserted into the center comes out with moist crumbs attached.
Add the Marshmallow Layer: Remove the brownies from the oven and immediately sprinkle the miniature marshmallows evenly over the hot surface.
Return to the Oven: Place the pan back in the oven for 2-3 minutes, just until the marshmallows get puffy and slightly melted.
Create the Peanut Butter Topping: While the marshmallows are melting, quickly mix the creamy peanut butter, powdered sugar, and melted butter in a small bowl until smooth.
Spread the Topping: Remove the pan from the oven. Drop spoonfuls of the peanut butter mixture over the melted marshmallows. Using an offset spatula, gently spread the peanut butter over the marshmallow layer. It’s okay if it’s not perfect; a swirled look is beautiful!
Cool Completely: This is the hardest part! Let the bars cool completely in the pan on a wire rack, for at least 4 hours, or until set. For best results and cleaner cuts, you can chill them in the refrigerator for an hour before slicing.
The perfect combination of fudgy, gooey, and creamy in every single bite.
Pro Tips for Irresistible Results
Want to ensure your Marshmallow Peanut Butter Brownie Bars are bakery-level perfect? Follow these simple tips.
Don’t Overbake the Brownies: The key to a fudgy base is to slightly underbake the brownie layer. Remember, they’ll cook a little more when you put them back in the oven with the marshmallows.
Use Parchment Paper: Lining the pan is a must. These bars are gooey, and the parchment paper “sling” will make lifting them out for easy cutting a breeze.
Chill for Clean Slices: For those picture-perfect squares, it’s essential to let the bars chill and set completely. A brief stint in the fridge will firm them up, allowing for much cleaner cuts. Use a large, sharp knife and wipe it clean between each slice.
Work Quickly with the Topping: Once the marshmallows come out of the oven, they start to set fast. Have your peanut butter topping mixed and ready to go so you can spread it while the marshmallow layer is still soft and pliable.
If you’re looking for another fantastic treat, you should check out these delightful brownie bottom mini cheesecakes. They are always a crowd-pleaser!
Fun Variations to Try
While this recipe is incredible as is, it’s also a great canvas for your creativity. For a different kind of sweet and savory combo, give our bacon jam cheeseburger sliders a try for dinner first!
Add a Salty Crunch: Sprinkle some crushed pretzels or flaky sea salt over the peanut butter topping before it sets.
Mix-in Madness: Add a cup of chocolate chips, peanut butter chips, or chopped nuts to the brownie batter for extra texture.
Use Crunchy Peanut Butter: If you love a bit of texture, swap the creamy peanut butter for a crunchy variety in the topping.
Storing Your Brownie Bars
To keep your Marshmallow Peanut Butter Brownie Bars fresh, store them in an airtight container at room temperature for up to 3 days. If your kitchen is particularly warm, you can store them in the refrigerator, but let them sit at room temperature for about 15-20 minutes before serving to allow the layers to soften up. I don’t recommend freezing these bars, as the marshmallow texture can change upon thawing.
Yes, you can use an equivalent amount of marshmallow fluff (creme). After the brownie layer is baked, drop spoonfuls of fluff over the top and gently spread it before adding the peanut butter layer. You won’t need to return it to the oven before adding the peanut butter topping.
A standard creamy peanut butter like Jif or Skippy works best for this recipe. Natural peanut butters can have a grittier texture and may separate, which can affect the consistency of the topping.
The secret to clean cuts is to chill the bars thoroughly. Once they have cooled completely at room temperature, place them in the refrigerator for at least 1 hour. Use a large, sharp knife, press straight down, and wipe the blade clean with a damp paper towel between each cut.
Store the bars in an airtight container at room temperature for up to 3 days. If your home is very warm, you can refrigerate them to prevent them from becoming too soft.
Absolutely! To double the recipe, use a 9×13 inch baking pan. You will also need to increase the baking time for the brownie layer by about 5-10 minutes. Keep an eye on it and test with a toothpick for doneness.
Marshmallow Peanut Butter Brownie Bars Recipe
FL Recipes
Marshmallow Peanut Butter Brownie Bars (The Ultimate Fudgy Treat)
Discover the ultimate fudgy treat with these Marshmallow Peanut Butter Brownie Bars. This easy recipe features a rich brownie base, a gooey marshmallow center, and a creamy peanut butter topping for a truly decadent dessert experience.
Preheat your oven to 350°F (175°C). Grease an 8x8 inch baking pan and line it with parchment paper, leaving an overhang on the sides to use as handles later.
In a large bowl, whisk together the melted butter and granulated sugar until well combined. Beat in the eggs one at a time, followed by the vanilla extract.
In a separate bowl, whisk together the all-purpose flour, cocoa powder, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix.
Pour the batter into your prepared pan and spread it into an even layer. Bake for 20-25 minutes, or until a toothpick inserted into the center comes out with moist crumbs attached.
Remove the brownies from the oven and immediately sprinkle the miniature marshmallows evenly over the hot surface.
Place the pan back in the oven for 2-3 minutes, just until the marshmallows get puffy and slightly melted.
While the marshmallows are melting, quickly mix the creamy peanut butter, powdered sugar, and melted butter in a small bowl until smooth.
Remove the pan from the oven. Drop spoonfuls of the peanut butter mixture over the melted marshmallows. Using an offset spatula, gently spread the peanut butter over the marshmallow layer.
Let the bars cool completely in the pan on a wire rack, for at least 4 hours, or until set. For best results and cleaner cuts, you can chill them in the refrigerator for an hour before slicing.
Nutrition
Calories: 250kcalProtein: 4gFat: 14gFiber: 2g
Notes
Pro Tip: For perfectly clean slices, chill the bars in the refrigerator for at least one hour before cutting. Storage: Store in an airtight container at room temperature for up to 3 days.
I hope you love these incredible Marshmallow Peanut Butter Brownie Bars as much as I do! They are truly one of the most decadent and satisfying desserts you can make. If you try this recipe, I’d love to hear about it. Leave a comment below or share a picture of your creation on Pinterest. Happy baking!
Get the recipe for these unbelievably delicious layered brownie bars!
Hi, I’m Emily Carter, and welcome to FL Recipes! I share simple, healthy recipes that make cooking easy, fun, and delicious for everyone. more about me »
