S’mores Brownie Bars with Graham Cracker Crust
Last Fourth of July, my sister banned me from the firepit after I torched three marshmallows in a row — black, not golden, every single time. I stood there holding a charred stick, genuinely annoyed, while the kids were already on their fourth s’more. That was the moment I decided to take the whole thing indoors. What I didn’t expect was that the oven version would make everyone forget the firepit entirely.
These s’mores brownie bars give you everything you love about the campfire classic — a dense, fudgy chocolate base, sticky toasted marshmallows, and shards of graham cracker for crunch — without the smoke, the sticks, or the burnt fingers. Prep takes 10 minutes, the oven does the rest, and you get 16 bars that hold together cleanly when you cut them.
Pro Tip
The mistake most people make: broiling the marshmallows on a fully hot brownie straight from the oven. The residual heat softens the marshmallows before the broiler even gets to them, so they collapse into a flat, wet layer instead of puffing and browning. Let the brownie cool for at least 8 minutes before adding the toppings, then broil. That short rest is the difference between a marshmallow that caramelizes on top while staying pillowy underneath, and one that just melts into a sticky puddle.
Graham crackers are widely available in the cookie aisle — look for the honey variety for the best caramel note. If you can’t find them, digestive biscuits work as a straight swap and bring a slightly less sweet, more buttery flavor. For chocolate chips, semi-sweet (around 50–60% cocoa) gives the right balance of richness without overpowering the marshmallow. Mini marshmallows brown more evenly under the broiler than large ones cut up, so grab a bag if you can.
S’mores Brownie Bars with Graham Cracker Crust
16
servings10
minutes25
minutes408
kcal8
minutes43
minutesIngredients
1/2 cup unsalted butter (113g)
2 cups semi-sweet chocolate chips (340g)
3 large eggs
1 tbsp vanilla extract
1 cup granulated sugar (200g)
1 1/4 cups all-purpose flour (155g)
1/4 tsp baking soda
1/2 tsp ground cinnamon
3 milk chocolate bars (approx. 4.4 oz / 125g each), divided
8 graham crackers (or digestive biscuits), broken into rough pieces
1 bag miniature marshmallows, 10 oz (280g)
Directions
- Preheat your oven to 350°F (175°C) and grease a 9×13 inch (23x33cm) baking pan. Line with parchment too — it makes lifting the bars out completely effortless.
- Melt butter and chocolate chips together in a large microwave-safe bowl in 30-second bursts, stirring between each. Stop when the mixture looks glossy and smooth — if you can still see a few unmelted chips, the residual heat will finish the job without scorching.
- Whisk in eggs and vanilla until fully combined. The batter should look thick and ribbon-like when you lift the whisk — that’s the eggs giving you that fudgy pull.
- Stir in sugar, flour, baking soda, and cinnamon until just combined. Don’t overmix once the flour goes in — stop as soon as no dry streaks remain.
- Chop 1½ chocolate bars into rough chunks and fold them into the batter, then spread evenly into the prepared pan. Uneven chunks melt at different rates, which creates pockets of molten chocolate in the final bar.
- Bake for 20–22 minutes, until a toothpick inserted in the center comes out with just a few moist crumbs. A clean toothpick means overbaked — you want crumbs, not wet batter, not nothing.
- Let the brownie rest for 8 minutes, then scatter marshmallows, chopped remaining chocolate, and broken graham crackers evenly over the top. That 8-minute rest is the key step from the pro tip — don’t skip it.
- Broil on high for 2–3 minutes, watching constantly. You’re looking for marshmallows that are deeply golden with dark spots — the same color as a campfire s’more, with a faint smell of caramel, not burning sugar.
- Cool for at least 10 minutes before cutting into 16 squares. A sharp knife wiped clean between cuts gives you bars with clean edges instead of dragged marshmallow streaks.
Variations
For a darker, less sweet base, swap the semi-sweet chips for 70% dark chocolate chips — the bittersweet contrast against the marshmallow is sharper and works well for adults. If you want a vegan version, use dairy-free butter, vegan chocolate chips, and a plant-based marshmallow brand (most standard marshmallows contain gelatin, so check the label).
Serving Suggestions
A scoop of vanilla ice cream placed on a warm bar melts into the gaps left by the marshmallows, which is exactly as good as it sounds. Lightly whipped cream with no added sugar keeps the focus on the chocolate. Cold whole milk, straight from the fridge, cuts through the richness better than almost anything else.
FAQ
How do I store leftover brownie bars?
Keep them in an airtight container in the fridge for up to 4 days. To reheat, 15–20 seconds in the microwave brings the marshmallow back to a soft, sticky texture without drying out the brownie base.
Can I make these ahead of time?
Yes — bake the brownie base up to a day ahead and store it covered at room temperature. Add the marshmallow topping and broil just before serving, so the marshmallows stay puffed rather than deflating overnight.
My marshmallows browned unevenly — what went wrong?
The most common cause is uneven placement: marshmallows piled on top of each other brown on the outside while the ones underneath barely color. Spread them in a single layer before broiling. After testing this recipe three times in my own kitchen, I also found that rotating the pan halfway through the broil makes a real difference — though it does make you wonder whether a kitchen torch would give you even more control.
