Marshmallow Brownie Bars Recipe

If you’re looking for a treat that’s rich, gooey, and just a little bit magical, you’ve come to the right place! I absolutely love this Marshmallow Brownie Bars Recipe because it combines that classic fudgy brownie texture with swirls of marshmallow fluff that add a whimsical, sweet surprise in every bite. Whether you’re making it for a cozy night in, a family gathering, or even just to treat yourself, these bars never fail to impress. Stick with me, and I’ll walk you through every step to get them just right!

this Recipe

Ingredients You’ll Need

Each ingredient plays a special role here. You’ll want good-quality cocoa powder for that deep chocolate flavor, and don’t skip the cornstarch—it helps create the perfect chewy texture. Plus, the marshmallow creme is the star that makes these brownies unforgettable.

• White granulated sugar: Provides sweetness and helps with the chewy texture.
• Large eggs & egg yolk: These add richness and help bind the brownies together.
• Unsalted butter: Melted for smooth incorporation and buttery flavor.
• Pure vanilla extract: A flavor enhancer that rounds out the chocolate.
• Oil (canola or vegetable): Keeps the brownies moist and tender.
• All-purpose flour: The structure builder, but just enough to keep things fudgy.
• Unsweetened cocoa powder (Dutch-processed preferred): For that intense, rich chocolate flavor.
• Cornstarch: Works wonders for chewiness – not a common ingredient in brownies, but trust me on this!
• Salt: Balances sweetness and intensifies the flavors.
• Semi-sweet chocolate chips: Adds melty pockets of chocolate that everyone loves.
• Marshmallow creme: This gooey swirl turns ordinary brownies into a showstopper.

Variations

I love that this Marshmallow Brownie Bars Recipe is so versatile. I often experiment with different mix-ins or toppings depending on my mood and what I have in my pantry. The beauty of brownies is how forgiving they are—so go ahead and make it your own!

• Nutty twist: I’ve stirred in chopped walnuts or pecans before, and the crunch pairs beautifully with the gooey marshmallow.
• Peanut butter swirl: Adding dollops of peanut butter along with the marshmallow fluff is my go-to when I want a richer, more decadent bar.
• Dietary swap: You can swap the oil for melted coconut oil for a slight tropical note or use dairy-free butter to make these bars vegan-friendly (just use flax eggs!).
• Seasonal flair: Around the holidays, I sprinkle peppermint bits or add a dash of cinnamon to bring a festive spirit.

How to Make Marshmallow Brownie Bars Recipe

Step 1: Prep Your Pan and Dry Ingredients

Start by preheating your oven to 325°F. I like to spray a 9×9-inch baking pan with nonstick spray, then line the bottom and two sides with parchment paper and spray again—this saves you a lot of headache when it comes time to remove the bars. Next, sift together the flour, cocoa powder, and cornstarch to ensure no lumps. Add the salt in and give it a gentle whisk to combine. This step helps you get evenly mixed batter later on, trust me, it makes a difference!

Step 2: Whip Up the Eggs and Sugar

Using a mixer with a whisk attachment, beat your sugar, eggs, and extra egg yolk on high speed for a full five minutes. When I first tried this recipe, I underestimated this step—don’t skip it! The mixture should become pale and slightly thickened, which brings lightness and helps the brownies rise just enough without being cakey.

Step 3: Blend in the Butter, Oil, and Vanilla

While your eggs and sugar are whipping, melt the butter in the microwave and let it cool to avoid scrambling the eggs. Then add the butter, oil, and vanilla to the mix on low speed, combining gently until smooth. This mixture is the base of your fudgy indulgence.

Step 4: Bring it All Together—Dry Ingredients and Chocolate Chips

Next, slowly add your dry ingredients to the wet mixture—mix on low and stop as soon as everything is just combined. Don’t overmix; overworked flour can make your brownies dense. Fold in the chocolate chips with a rubber spatula—I like to reserve a few to sprinkle on top for extra chocolate goodness.

Step 5: Add the Marshmallow Fluff Swirls

Pour the batter into your prepared pan and smooth it out evenly. Then, microwave the marshmallow creme for 20-30 seconds just to soften it a bit, and dollop teaspoon-sized blobs over the batter. Using a butter knife, gently swirl the marshmallow fluff into the batter to create beautiful marbled pockets of gooey sweetness—don’t overdo it or it will all blend in.

Step 6: Bake and Cool

Bake your bars for 45 to 55 minutes. The trick is that the toothpick should come out with just a few moist crumbs, but not wet batter. I’ve learned that ovens vary, so start checking around the 45-minute mark. Once done, cool your brownies completely on a wire rack before cutting to help them set up perfectly and avoid messy edges.

How to Serve Marshmallow Brownie Bars Recipe

Garnishes

I usually keep it simple and garnish with just a light dusting of powdered sugar or a few extra chocolate chips on top before baking. When I want to dress them up, a drizzle of caramel sauce or a sprinkle of chopped nuts adds great texture and flavor contrast.

Side Dishes

These bars are decadent enough to stand alone, but if you want to make it a full dessert experience, pairing them with fresh berries or a scoop of vanilla ice cream takes it over the top. For parties, a hot cup of coffee or milk is always a crowd-pleaser alongside these brownies.

Creative Ways to Present

For celebrations, I’ve arranged these bars on a pretty platter with mini marshmallows scattered around and a few edible flowers for a festive look. Another fun idea is cutting them into bite-sized squares and stacking them on a dessert tower or serving with skewers for a party-friendly treat.

Make Ahead and Storage

Storing Leftovers

I keep leftover bars in an airtight container at room temperature for up to 3 days. They stay moist and delicious, but if your kitchen is warm, you can refrigerate them to keep things fresh longer—just bring them back to room temp before serving for the best taste.

Freezing

When I’ve made big batches, I freeze these bars individually wrapped in parchment and then in a freezer bag. They freeze beautifully for up to 3 months. When you’re ready, just thaw at room temperature or warm gently in the microwave for that fresh-baked vibe.

Reheating

To reheat, I pop a bar in the microwave for about 15-20 seconds. This warms the chocolate chips and marshmallow fluff just enough to make it gooey again without making it tough. Oven reheating (around 300°F for 5-7 minutes) works too if you want more even heat.

FAQs

Final Thoughts

Honestly, this Marshmallow Brownie Bars Recipe has become one of my absolute favorites to make and share. The texture, the marshmallow swirl, and the rich chocolate hit all the right notes every single time. It’s a go-to when I want to wow guests without a ton of fuss. I hope you’ll give it a try—it’s the kind of recipe that makes you smile with every bite and ask yourself why you haven’t made it sooner. Happy baking, friend!

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