Easy S’mores Brownies with Box Mix

These s’mores brownies with box mix are the dessert I make when I want that campfire flavor without the campfire. A box of brownie mix gets doctored up until it tastes better than from-scratch, then it bakes right on top of a layer of graham crackers and gets crowned with toasted mini marshmallows. You get the fudgy chocolate, the crunch, and the gooey toasted top in one pan, any time of year. And if you’d rather skip the box mix, scroll down for my from-scratch brownie base too.

Since you are here, make sure to take a look at my 10 secrets to make brownie mix better, these brownie mix cookies, as well as these lazy girl pumpkin cheesecake brownies.

Why this is the best easy s’mores brownie recipe

These homemade s’mores brownies are one of those desserts you don’t think about until you’ve had them once, and then you want them on repeat. Starting with brownie mix saves you time without sacrificing anything, because a few simple swaps make the box taste like a from-scratch batch. You get a fudgy, rich brownie, a built-in graham cracker crust, and a toasted marshmallow top, all from one easy recipe.

Why you need to make this recipe

• Quick and easy. The box mix does the heavy lifting, so these come together fast.
• The best texture combo. Fudgy brownie, crunchy graham cracker bottom, and ooey gooey toasted marshmallow in every bite.
• Crowd pleaser. Perfect for a potluck, a BBQ, or anytime you need a dessert that disappears fast.
• Beginner friendly. Simple ingredients and no fussy steps. The hardest part is waiting for them to cool before slicing.
• Better than the box. A handful of easy upgrades (egg yolks, coffee, a little extra chocolate) make these taste homemade.

Ingredients for these delicious s’mores brownies

Here are the ingredients you will need to make this s’mores brownies recipe. Make sure to scroll down to the recipe card for the full detailed ingredient measurements. 

• Brownie mix – A higher-quality box mix makes a noticeable difference in the final taste. Use one sized for an 8×8 inch pan.
• Egg yolks – I use yolks instead of whole eggs to make these extra fudgy and rich. You can use whole eggs if that’s what you have.
• Vegetable oil or butter – Oil keeps things easy, but melted butter makes them even richer.
• Coffee – Freshly brewed coffee deepens the chocolate flavor. Swap in hot water if you’d rather skip it.
• Vanilla extract
• Salt
• Chocolate chips – Semisweet or milk chocolate both work.
• Graham crackers – Whole sheets to line the bottom for that built-in s’mores crust.
• Mini marshmallows – These bring the whole dessert together.
• Nonstick cooking spray – My trick for slicing. It keeps the marshmallows from sticking to the knife.

How to make these s’mores fudgy brownies

Here’s how to make s’mores brownies with box mix. Scroll down to the recipe card for the full detailed instructions.

1. Preheat the oven to 325F and line an 8×8 inch pan with parchment paper, leaving an overhang on the sides for easy lifting later.
2. Layer the graham cracker sheets across the bottom of the pan in a single layer, breaking some to fit so they cover the whole surface.
3. In a large bowl, mix the brownie mix, egg yolks, hot brewed coffee, oil, vanilla, and salt until a thick batter forms. Fold in the chocolate chips.

4. Pour the batter evenly over the graham crackers and spread into an even layer. Bake for 40 minutes.
5. Pull the brownies out and top with the mini marshmallows. Return to the oven for another 3 to 4 minutes.

1. Using a kitchen torch or the broiler, toast the marshmallows until golden. Watch closely so they don’t burn.
2. Let the brownies cool fully before slicing. Spray your knife with nonstick spray for clean cuts.
3. Slice and enjoy your toasty s’mores brownies.

How to make s’mores brownies in a 9×13 pan

This recipe is written for an 8×8 inch pan, which makes 16 squares. If you need a crowd-size batch, double everything and bake it in a 9×13 pan. Here is how to scale it:

• Double the brownie mix (use two boxes, or one large family-size box meant for a 9×13), the egg yolks, oil, coffee, vanilla, salt, and chocolate chips.
• Use about 8 to 9 graham cracker sheets to cover the bottom of the 9×13 in a single layer.
• Bake at the same 325F, but add roughly 8 to 12 minutes to the bake time. Start checking at the original time plus 8 minutes and look for set edges with a fudgy center.
• Top with 3 to 4 cups of mini marshmallows and toast as usual.

Pro tip: A 9×13 is roughly double the area of an 8×8, so doubling the recipe is the cleanest scale. Keep the oven temp the same and judge doneness by the center, not just the clock.

How to make these s’mores brownies from scratch

If you’d rather skip the box mix, this is the homemade brownie base I’ve been perfecting all year. It’s rich, fudgy, and has that crackly shiny top from beating the eggs and sugar long enough to get them properly ribbon-y. Use this as the brownie layer, then build the s’mores exactly the same way (graham crackers on the bottom, marshmallows toasted on top).

Ingredients for the from-scratch brownie layer

• ½ cup butter, salted or unsalted
• 3 tbsp neutral oil, like vegetable or grapeseed
• 4 oz 70% dark chocolate, chopped
• 2/3 cup Dutch process cocoa powder
• 1 tsp instant espresso powder
• 2 large eggs, room temp
• 1 egg yolk
• 1 cup granulated sugar
• ½ cup powdered sugar
• 1½ tsp vanilla extract
• ½ cup all-purpose flour
• 1 tbsp cornstarch
• ½ tsp kosher salt

Plus the graham crackers and mini marshmallows from the main recipe.

How to make the from-scratch s’mores brownies

1. Preheat the oven to 350°F and line an 8×8 inch metal pan with parchment paper, leaving an overhang for easy lifting. Layer the graham cracker sheets across the bottom in a single layer, just like the box mix version.
2. In a heatproof bowl, combine the butter, chopped chocolate, and oil. Melt gently in 30-second bursts in the microwave (or over a double boiler), then stir in the cocoa powder and espresso powder until smooth. Let it cool slightly.
3. In a large bowl, beat the eggs, egg yolk, granulated sugar, powdered sugar, and vanilla on high speed for 3 to 6 minutes, until the mixture is thick, pale, and ribbon-y. This step is where that shiny crackle top is born, so don’t rush it!
4. With the mixer on low, slowly pour in the slightly cooled chocolate-butter mixture and mix until just combined.
5. Sift the flour, cornstarch, and salt into the batter and gently fold them in with a spatula until no streaks remain.
6. Pour the batter over the graham crackers in the prepared pan, smooth the top, and tap the pan once on the counter to release any big air bubbles. Bake for 23 to 25 minutes, or until a toothpick comes out with moist crumbs.
7. Let the brownies cool completely in the pan. This is the key step for clean layers, so don’t rush it.
8. Once fully cooled, top with 2 cups of mini marshmallows and bake at 350°F for 7 to 8 minutes, until the marshmallows are puffed and lightly golden. For that extra bonfire char, hit the tops with a kitchen torch right after.
9. Let the marshmallow layer set for a few minutes, then slice with a knife sprayed with nonstick spray for clean cuts.

From-scratch vs box mix: which version should you make?

Both versions taste incredible, and the box mix shortcut is genuinely fantastic when you’re short on time. The from-scratch version is richer, fudgier, and gives you that pastry-shop crackle top. If you’re making these to impress someone or for a special occasion, go from scratch. If you want a campfire dessert ready in under an hour, the box mix is your best friend.

Frequently asked questions – FAQ