When I’m in the mood to bake something ridiculously indulgent — the kind of dessert that’s unapologetically rich, gooey, and crowd-pleasing — these S’mores Oreo Brownie Bars are my go-to. They’re a dessert lover’s dream: buttery graham cracker crust, a layer of Oreo cookies, fudgy brownie batter, and toasted marshmallows on top. Yes, it’s a lot. And yes, they are absolutely worth it.
The first time I made these bars, I brought them to a potluck where people literally stopped mid-conversation after the first bite. They’re that good. It’s like your favorite campfire s’mores, a box of Oreos, and a pan of brownies all decided to team up and become the ultimate dessert.
Why I Love These S’mores Oreo Brownie Bars
- They’re rich, gooey, and full of texture — every bite is a flavor bomb.
- No special tools or complicated steps, just layers of deliciousness.
- Great for feeding a crowd — a small square goes a long way.
- Perfect for summer parties, game nights, or whenever you’re craving chocolate.
- The marshmallows get beautifully golden and gooey, just like a toasted s’more.
Ingredients You’ll Need
(Makes 16 bars | Prep Time: 15 minutes | Bake Time: 35–40 minutes)
For the crust:
- 2 cups graham cracker crumbs
- 1/2 cup (1 stick) unsalted butter, melted
For the layers:
- 1 package Oreo cookies (about 36 cookies)
- 1 box brownie mix (plus eggs, oil, and water as called for on the box)
- 2 cups mini marshmallows
How I Make S’mores Oreo Brownie Bars (Step-by-Step)
- Preheat and Prep
I preheat my oven to 350°F and line a 9×13-inch baking pan with parchment paper. This makes it much easier to lift the bars out later for slicing. - Make the Crust
In a bowl, I mix the graham cracker crumbs and melted butter until combined. I press this mixture firmly into the bottom of the prepared pan to form a buttery base. - Layer the Oreos
Next, I line the entire surface of the graham crust with whole Oreos. I don’t crush them — just lay them down flat, side by side. They soften while baking and create a fantastic middle layer. - Mix and Pour the Brownie Batter
I prepare the boxed brownie mix according to the package directions. Then I pour the batter over the Oreos, spreading it out evenly to cover them completely. - Bake
I bake the bars for about 30–35 minutes, or until the brownie layer is set but still soft in the middle. - Add Marshmallows and Toast
Once the brownies are baked, I pull the pan from the oven and sprinkle the mini marshmallows over the top. Then I return it to the oven for another 5–7 minutes — just enough for the marshmallows to puff up and turn lightly golden. - Cool and Slice
I let the bars cool completely in the pan before lifting them out and slicing into squares. A sharp knife (and maybe a little patience) helps get clean cuts through the gooey layers.
My Tips for the Best S’mores Oreo Brownie Bars
- Line your pan — trust me, these are sticky. Parchment paper is a lifesaver.
- Let them cool fully before slicing, or they’ll fall apart (I know it’s hard to wait).
- Use a kitchen torch if you want perfectly toasted marshmallow tops without overbaking.
- Want them extra gooey? Slightly underbake the brownie layer.
Fun Variations I’ve Tried
- Swapping regular Oreos for golden, peanut butter, or mint Oreos.
- Adding a layer of peanut butter cups or chocolate chunks between the Oreos and brownies.
- Using marshmallow fluff as a swirl inside the brownie batter for more gooeyness.
- Making them in muffin tins for individual s’mores brownie cups.
What I Serve with These Bars
- A scoop of vanilla or cookies-and-cream ice cream.
- Cold milk or iced coffee to cut through the richness.
- Crushed graham cracker dust or melted chocolate drizzle on top when serving.
- As part of a dessert board alongside cookies and rice krispie treats.
Frequently Asked Questions
Q: Can I make these ahead of time?
A: Yes! They actually slice better the next day once they’ve set completely.
Q: Do I have to use a boxed brownie mix?
A: Nope — homemade brownie batter works great too. Just use enough for a 9×13 pan.
Q: Can I store leftovers at room temp?
A: Yes — just keep them covered. They’ll stay fresh for 2–3 days or longer in the fridge.
Q: How do I keep the marshmallows from getting too dark?
A: Keep an eye on them in those last few minutes. You want golden, not burnt.
Why You Need to Try These S’mores Oreo Brownie Bars
If you love rich, chocolatey desserts and you’re into that sweet-salty-slightly-crunchy texture combo, this recipe is a must-bake. It’s bold, messy in the best way, and over-the-top delicious. The layers melt into each other just enough to make every bite feel indulgent — and if you’re bringing dessert to a gathering, this one will steal the spotlight.
I hope you give them a try and make them your own. Just be warned: once you taste them, you may never look at s’mores or brownies the same way again.
