Desserts
This brownie recipe with chocolate chips and marshmallows delivers the ultimate dessert experience—rich, fudgy layers topped with gooey melted rivers of chocolate and marshmallow. The secret lies in precise baking times and ingredient ratios that balance density and indulgence.
I perfected this version after years of testing, ensuring every bite has that perfect contrast of tender base and molten sweetness.
The chocolate chips melt into pockets of molten goodness, while the marshmallows create those signature caramelized rivers that make this brownie irresistible. This recipe uses a single-layer pan for even baking, with a focus on high-quality ingredients that elevate the flavor.
The result? A dessert that’s restaurant-quality at home, with a texture that’s neither cakey nor overly dense.
What sets this apart is the two-stage baking process—first for the base, then to melt the toppings just right. The marshmallows puff and caramelize beautifully, while the chocolate chips stay gooey, creating that perfect balance of textures.
Each slice is a masterpiece of decadence and simplicity, designed to impress without requiring advanced skills.
Serve warm with a scoop of vanilla ice cream or a dollop of whipped cream to enhance the experience. This brownie is ideal for special occasions or when you crave a dessert that feels like a hug. Let’s get baking—your taste buds will thank you.
Ingredients for brownie recipe with chocolate chips and marshmallows
High-quality ingredients transform into decadent, gooey brownies with molten chocolate and marshmallow rivers.
| Ingredient | Amount | Notes |
|---|---|---|
| Unsalted Butter 🧈 | 1 cup | Cold, cubed for even melting |
| Granulated Sugar 🍚 | 2 cups | Superfine preferred for smoothness |
| Light Brown Sugar 🍚 | ½ cup | Packed, for moisture balance |
| All-Purpose Flour 🌾 | 1 ½ cups | Sifted for light texture |
| Cocoa Powder 🍫 | ¾ cup | Natural, unsweetened |
| Baking Powder 🧂 | ½ tsp | Aluminum-free preferred |
| Salt 🧂 | ½ tsp | Diamond Crystal kosher |
| Vanilla Extract 🌿 | 1 tbsp | Pure, high-quality |
| Large Eggs 🥚 | 2 whole | Room temperature |
| Semisweet Chocolate Chips 🍫 | 2 cups | Enjoy Life brand for allergies |
| Mini Marshmallows 🧸 | 3 cups | Extra for dramatic rivers |
| Extra-Virgin Olive Oil 🫒 | 1 tbsp | For greasing pan |
The cocoa powder and chocolate chips are non-negotiable for that deep, fudgy flavor. Ghirardelli Natural Cocoa or Valrhona elevate the base, while Enjoy Life chocolate chips ensure allergy-friendly indulgence. For the marshmallows, Kraft Jet-Puffed or Dandies create those signature caramelized rivers—anything smaller than mini marshmallows won't melt into proper rivers. The butter should be cold and cubed to prevent overmixing, which keeps the texture tender rather than dense. I always grab my butter from Whole Foods for its high-fat content—it makes all the difference in richness.
No semisweet chocolate chips? Chopped dark chocolate (60-70%) works in a pinch, but melt it first for even distribution. Short on marshmallows? White chocolate chips or toffee bits add a similar gooey texture, though they won’t caramelize like marshmallows. For the sugar, superfine is ideal, but pulse regular granulated sugar in a food processor if that’s what you’ve got. The vanilla extract should be pure—Nielsen-Massey or McCormick are reliable brands. And if you’re baking in a high-altitude area, reduce the baking powder to 0.25 tsp to prevent over-rising.
These brownies are best served warm, straight from the oven, with that molten goodness still flowing. Store any leftovers in an airtight container at room temperature for 3-4 days, though they’ll lose some of that gooey magic. For longer storage, freeze the entire pan (unwrapped) for up to 3 months
Why You'll Love This Recipe
- One-Bowl Wonder: I swear by this recipe because it’s that simple—just melt the butter, mix everything in one bowl, and bake. No fancy techniques, no extra pans, and honestly? The kids can help with the chocolate chip and marshmallow folding.
- Campfire Vibes: Between us, this is my go-to for movie nights, potlucks, or even a lazy Sunday. The marshmallows toast slightly in the oven, giving it that campfire s’mores energy without the fire pit.
- Budget Dessert Hero: Uses pantry staples—no weird ingredients—and stretches to feed a crowd. Leftovers? They disappear faster than I can say “second slice.” (Yes, even on a Tuesday night.)
Step-by-step instructions for rich, fudgy brownies with chocolate chip-marshmallow rivers
Here's how to create the ultimate brownie experience—where every bite delivers a perfect balance of dense, fudgy base and gooey, melted rivers of chocolate and marshmallow.
Prepare the Pan and Preheat the Oven
Preheat your oven to 350°F—this is the magic temperature for achieving that perfect balance of fudgy texture and crispy edges. Line an 8x8-inch baking pan with parchment paper, leaving an overhang on the sides for easy removal. Then, lightly grease the parchment with the 1 tablespoon extra-virgin olive oil using a paper towel. This ensures the brownies don't stick, even in the corners.
I always double-check the oven temperature with an oven thermometer—some ovens run hot, and you want that 350°F to be precise. The oil coating also helps create that beautiful, glossy finish on the top of the brownies. Once the oven is fully preheated, you're ready to start building the base.
Melt the Butter and Mix the Wet Ingredients
In a large microwave-safe bowl, melt the 1 cup unsalted butter in 30-second intervals, stirring between each interval until fully melted but not browned. Let it cool for 1 minute—this prevents the eggs from scrambling when added later. In a separate bowl, whisk together the 2 cups granulated sugar and 0.5 cup light brown sugar until evenly combined.
Add the melted butter to the sugar mixture and whisk vigorously for 1 minute until the sugars dissolve completely and the mixture is smooth. This step is crucial for creating a silky, even texture in your brownies. Next, stir in the 1 tablespoon vanilla extract—this adds depth of flavor that takes these brownies from good to extraordinary. The mixture should be fragrant and fully incorporated.
Combine Dry Ingredients and Fold in Chocolate
In a medium bowl, sift together the 1.5 cups all-purpose flour, 0.75 cup cocoa powder, 0.5 teaspoon baking powder, and 0.5 teaspoon salt. Whisk to remove any lumps and ensure an even distribution of cocoa. Gradually add this dry mixture to the wet ingredients, mixing on low speed with a hand mixer or whisk until just combined—you should still see some flour streaks. Overmixing develops gluten, which can make your brownies tough.
Remove the bowl from the mixer and fold in the 2 cups semisweet chocolate chips by hand using a silicone spatula. I like to press the chocolate chips into the batter slightly so they're evenly distributed throughout. This ensures every bite has pockets of rich, melted chocolate. The batter will be thick and fudgy—this is exactly what you want for that signature texture.
Layer the Marshmallows and Bake to Perfection
Pour half of the brownie batter into the prepared pan and spread it evenly with a spatula. Sprinkle half of the 3 cups mini marshmallows evenly over the batter, pressing them down gently so they adhere. Repeat with the remaining batter and marshmallows, creating a second layer. The marshmallows should cover the top completely—this is what creates those incredible melted rivers when baked.
Bake for 25-30 minutes until the edges are set but the center still looks slightly underdone. You'll know it's ready when a toothpick inserted into the center comes out with a few moist crumbs but no wet batter. The marshmallows should be golden brown and bubbly on top, with melted rivers beginning to form. If the top browns too quickly, tent the pan with foil for the last 5 minutes of baking.
Cool and Create the Ultimate Presentation
Remove the brownies from the oven and let them cool in the pan for 10 minutes. This allows the marshmallows to set slightly and the chocolate to firm up just enough to hold their shape when cutting. Use the parchment overhang to lift the brownies out of the pan and place them on a wire rack to cool completely for 1 hour. Patience here is key—cooling thoroughly ensures clean cuts and those perfect melted rivers when served.
Once fully cooled, cut the brownies into 9 equal squares using a sharp knife. For the most dramatic presentation, serve at room temperature so the marshmallow rivers are just beginning to melt. The contrast of the dense, fudgy base with the gooey, sweet rivers of chocolate and marshmallow is what makes these brownies unforgettable. Enjoy immediately for the ultimate indulgence!
Pro Tips For Making Brownie Recipe With Chocolate Chips And Marshmallows
- Melt Butter Slowly: I learned this the hard way—rushing butter over high heat creates steam that burns your sugar. Use medium-low heat and stir constantly until it’s just shimmering (not bubbling) before adding the sugars. That way, your brownies won’t taste like caramelized regret.
- Sift the Cocoa: Dense cocoa powder packs unevenly, leading to dry spots or a cakey texture. Sift it with the flour—twice—before mixing. Yes, it’s extra work, but your brownies will stay fudgy and uniform. (I skip this and still get compliments, but the texture is noticeably better when I don’t.)
- Fold in Marshmallows Last: Add them too early, and they’ll melt into a sticky mess before the batter sets. Wait until the last 30 seconds of mixing, then gently fold them in with a spatula—just enough to distribute, not crush. If you’re impatient like me, toss them in the oven raw and let the residual heat puff them up mid-bake.
- Bake Until Slightly Under: The edges should pull away from the pan, but the center should still jiggle like Jell-O. Overbaking turns marshmallows to rubber and brownies to hockey pucks. Pull them out early, tent with foil, and let them rest 5 minutes—they’ll firm up while staying gooey inside. (Your knife test is your enemy here; trust the visual.)
Pro cooking tips for this recipe
Perfect Baking Time
Bake your brownies for 25-30 minutes at 350°F—this is the sweet spot for achieving that signature fudgy texture with crisp edges. The marshmallows need time to puff and caramelize into those golden rivers, so don't rush it!
I use an oven thermometer to confirm my oven hits 350°F accurately, as home ovens often run hot or cold. 🌡️
Layering Like a Pro
Spread the batter evenly in the pan before adding marshmallows—uneven layers lead to uneven baking. Press the marshmallows down gently so they stick to the batter. This ensures they melt into perfect rivers rather than sliding off.
I like to use mini marshmallows because they create more dramatic rivers than larger ones. 🧸
Don't Overmix the Batter
Mix the dry ingredients into the wet just until combined—you should still see flour streaks. Overmixing develops gluten, which makes brownies tough instead of fudgy. I use a hand mixer on low speed for 10-15 seconds after combining, then switch to a spatula to fold in the chocolate chips.
This keeps the texture tender and rich. 💫
Two-Stage Baking Secret
Bake the brownies until the edges are set but the center still looks slightly underdone. The marshmallows should be golden brown with melted rivers forming. If the top browns too quickly, tent with foil for the last 5 minutes to prevent over-browning.
This two-stage approach ensures the marshmallows melt perfectly while the base stays fudgy. ✨
Cooling for Clean Cuts
Let the brownies cool in the pan for 10 minutes before transferring to a wire rack. This allows the marshmallows to set slightly and the chocolate to firm up. Cooling completely for 1 hour ensures clean cuts and those perfect molten rivers when served.
I always use a sharp knife dipped in hot water between cuts for clean edges. 🔪
Storage Tips for Freshness
Store leftovers in an airtight container at room temperature for 3-4 days, though they're best enjoyed fresh. For longer storage, freeze the entire pan (unwrapped) for up to 3 months.
Thaw at room temperature before serving to restore that gooey magic. I like to portion mine into individual squares for easy grab-and-go indulgence. ❄️
Nutrition facts
Frequently asked questions
Why do the marshmallows need to be mini size?
Mini marshmallows create the signature caramelized rivers that make these brownies special! Their smaller size allows them to melt into dramatic, gooey streams rather than staying as individual puffs. Larger marshmallows won't spread as much, giving you fewer rivers. For extra decadence, use 3 cups of mini marshmallows as called for in the recipe.
Can I make these brownies without an oven?
Unfortunately, no—this recipe requires baking to achieve the perfect fudgy texture and melted marshmallow rivers. However, you could try a stovetop skillet method by melting the butter and sugar in a pan, then adding the dry ingredients and cooking on low heat, but the texture won't be the same. The oven creates the ideal balance of heat for both the base and toppings.
How do I know when the brownies are fully baked?
They're done when the edges are set but the center still looks slightly underdone (a toothpick should come out with moist crumbs, not wet batter). The marshmallows should be golden brown with melted rivers forming. For 25-30 minutes at 350°F, check at the 25-minute mark—every oven varies! If the top browns too quickly, tent with foil for the last 5 minutes.
What's the best way to cut these brownies?
Use a sharp knife and dip it in hot water between cuts for clean edges. Warm the knife first, then wipe dry before each slice. Cutting when the brownies are at room temperature (after 1 hour of cooling) ensures the marshmallow rivers stay intact. For extra presentation, dust with powdered sugar or serve with a scoop of vanilla ice cream!
Can I substitute white chocolate for the chocolate chips?
Yes, but the flavor will be milder. Use 2 cups of white chocolate chips (melted first for even distribution) instead of semisweet. For a hybrid flavor, mix 1 cup semisweet and 1 cup white chocolate chips. The texture will still be gooey, but the taste will lean sweeter. Dark chocolate (60-70%) can also be used, but reduce to 1.5 cups for balance.