I’m so excited to share these Peanut Butter Marshmallow Brownies with you today! They’re the perfect combination of fudgy chocolate, creamy peanut butter, and pillowy marshmallow fluff all swirled together in one incredible dessert. Trust me, the moment these come out of the oven, with their gooey centers and that irresistible peanut butter-marshmallow marble effect, you’ll understand why they disappear so quickly at every gathering. Want to know the secret to getting those perfect swirls?
Why You’ll Love these Peanut Butter Marshmallow Brownies
If you’re craving a dessert that combines all the best flavors in one pan, these Peanut Butter Marshmallow Brownies are about to become your new obsession.
I mean, what’s not to love? Rich chocolate brownies swirled with creamy peanut butter and gooey marshmallow fluff create the ultimate texture contrast.
The sweet-salty combination hits all the right notes on your taste buds. They’re surprisingly simple to make, too—just mix, swirl, and bake. Perfect for potlucks, family gatherings, or those nights when you need something indulgent.
The parchment sling trick makes serving them neat and easy. Waiting for them to cool? That’s the hardest part.
What Ingredients are in Peanut Butter Marshmallow Brownies?
These decadent brownies combine three beloved flavors into one irresistible treat, and you probably have most of the ingredients in your pantry already.
- 1 batch brownie batter (homemade or from a box mix)
- ½ cup creamy peanut butter
- ¼ cup powdered sugar
- 2 tablespoons unsalted butter, at room temperature
- Pinch of salt
- ½ cup marshmallow fluff
For the best results, make sure your butter is truly at room temperature for easy mixing, and consider using a high-quality peanut butter without added sugars or oils for the richest flavor profile.
How to Make these Peanut Butter Marshmallow Brownies
Step 1: Prepare the Brownie Batter
Start with preparing 1 batch of your favorite brownie batter, whether homemade or from a boxed mix. You know that feeling when the chocolate aroma fills your kitchen? Nothing quite compares to that moment of anticipation.
Step 2: Make the Peanut Butter Mixture
In a medium bowl, combine ½ cup creamy peanut butter, ¼ cup powdered sugar, 2 tablespoons room temperature unsalted butter, and a pinch of salt.
Mix these ingredients until completely smooth and creamy—no lumps allowed in this velvety concoction.
Step 3: Preheat and Prepare the Pan
Preheat your oven to 350°F and line your baking pan with parchment paper, creating a sling with overhang on the sides.
This little trick makes removing the brownies later so much easier, and who doesn’t want hassle-free dessert?
Step 4: Layer the Brownie Batter
Pour your prepared brownie batter into the parchment-lined pan, spreading it evenly with a spatula.
The foundation of any good brownie is an even batter layer—it’s like creating the perfect canvas for our peanut butter and marshmallow artistry.
Step 5: Add the Peanut Butter and Marshmallow
Dollop the peanut butter mixture and ½ cup marshmallow fluff randomly over the brownie batter.
The contrast of the golden peanut butter and white marshmallow against the dark chocolate is simply gorgeous.
Step 6: Create the Swirl Pattern
Take a knife or a wooden skewer and gently swirl the dollops into the brownie batter, creating a marbled effect.
Don’t over-swirl, as we want distinct pockets of each flavor to surprise us with every bite.
Step 7: Bake to Perfection
Bake in the preheated oven for 26-32 minutes, or until the center is just set.
The edges might look slightly more done than the middle, which is exactly what we want for that perfect fudgy interior.
Step 8: Cool Completely Before Cutting
Allow the brownies to cool completely in the pan before attempting to cut them.
Patience is truly a virtue here—warm brownies might taste heavenly, but they’ll fall apart if cut too soon.
For the cleanest slices, you might even consider refrigerating them for an hour before cutting.
For a more efficient way to prepare your batter, a high-quality stand mixer will make this process significantly easier and more consistent.
What to Serve with Peanut Butter Marshmallow Brownies
These decadent brownies deserve equally delightful accompaniments. A scoop of vanilla ice cream creates the perfect hot-and-cold contrast when the brownies are slightly warmed.
For a more sophisticated touch, serve with a small glass of cold milk or a creamy coffee—the bitterness of coffee balances the sweet richness beautifully.
If you’re serving these at a dessert table, add some fresh berries on the side; strawberries and raspberries cut through the richness wonderfully.
For a truly indulgent experience, drizzle warm chocolate sauce over the top just before serving. These treats make an excellent afternoon pick-me-up with tea or the star of any dessert spread when entertaining.
Peanut Butter Marshmallow Brownies Substitutions and Variations
- Seasonal Twists: Add crushed candy canes during the holidays or orange zest in fall for seasonal flair.
- Topping Ideas: Finish with a sprinkle of flaky sea salt, a drizzle of caramel, or a dusting of cocoa powder to elevate these already amazing brownies.
Leftovers and Storage for these Peanut Butter Marshmallow Brownies
These decadent brownies actually taste even better the next day, when the flavors have had time to meld together. Here’s how to keep them at their best:
- Counter Storage: Store in an airtight container at room temperature for up to 3 days. Place parchment paper between layers to prevent sticking.
- Refrigerator: For longer freshness, refrigerate for up to a week. The cold firms up the peanut butter swirls beautifully.
- Freezer Option: These freeze wonderfully! Wrap individual brownies in plastic, then store in a freezer bag for up to 3 months.
When ready to enjoy, let refrigerated brownies come to room temperature for about 30 minutes.
For frozen brownies, thaw overnight in the refrigerator or microwave for 15-20 seconds for that just-baked texture.
Final Thoughts
These Peanut Butter Marshmallow Brownies represent comfort food at its finest—the interplay of fudgy chocolate, creamy peanut butter, and pillowy marshmallow creates an irresistible trio of flavors and textures.
They’re perfect for weekend baking when you want something special but not fussy, and they’re guaranteed to disappear quickly at potlucks and bake sales.
The beauty lies in their versatility: dressed up on a dessert plate for company, or wrapped in a lunch box for a midweek treat.
Sometimes the most memorable desserts are the ones that combine childhood favorites in unexpected ways—and these brownies do exactly that.