Thick, chewy, and irresistibly gooey, these s’mores cookie bars capture everything you love about the classic campfire treat. The cookie dough is flavored with crushed graham crackers for that unmistakable s’mores taste, then stuffed with a generous layer of milk chocolate and marshmallow fluff.
These s’mores cookie bars are the perfect warm-weather dessert, but honestly they’re great any time of year. The base is an easy cookie dough—similar to blondie or chocolate chip cookie dough—where part of the flour is replaced with crushed graham crackers to create that classic s’mores flavor. In the center you’ll layer milk chocolate (Hershey’s or your favorite milk chocolate) topped with marshmallow fluff, then finish with more graham cookie dough.
The result is a thick, fudgy bar with a melty layer of chocolate and an oozy marshmallow center.
Tip: Slice the bars while they’re still warm for an extra gooey, spoon-worthy treat. If you prefer neat squares like the photos, let them cool completely before slicing; the marshmallow will remain gooey but the cuts will be cleaner.
Making S’mores Cookie Bars
Start by preparing the graham cookie dough.
- Whisk together the melted butter, brown sugar and granulated sugar until the butter is fully incorporated and no longer pooling on top of the sugar.
- Add the egg, an extra egg yolk, and vanilla extract, whisking until combined. The extra yolk keeps the bars extra chewy.
- Stir in the flour and salt by hand until the mixture is uniform; salt helps balance all the sweetness.
- Fold in the crushed graham crumbs until evenly distributed.
Next, assemble the bars.
- Reserve about 1 cup of cookie dough for the top layer.
- Press the remaining dough into the bottom of a lined 8×8 inch (20×20 cm) pan, creating an even base.
- Place an even layer of milk chocolate over the bottom dough.
- Four regular Hershey’s bars (or equivalent) usually cover the pan; use whole bars and break pieces as needed to fill gaps.
- Spoon about 1½ cups of marshmallow fluff (marshmallow creme) over the chocolate and spread evenly.
- Putting the chocolate under the fluff makes the bars easier to slice after baking.
- Form the reserved dough into small balls, flatten them into discs, and place them across the marshmallow layer to cover as much surface as possible.
- It’s fine if small patches of marshmallow remain exposed—these will puff and create gooey pockets while baking.
Bake the bars for about 30–35 minutes. The top should be golden brown when done. If some marshmallow is exposed it will puff and bubble, creating pockets of gooey marshmallow; if fully covered by dough, the marshmallow will stay more even in the center.
Ingredient Substitutions
Graham Crumbs: If you can’t find graham crackers, crushed digestive biscuits are a very good substitute and work well for bakers in the UK or Australia.
Chocolate: Use any milk, semi-sweet, or dark chocolate you prefer. I like whole chocolate bars because they melt into a more authentic, gooey s’more texture, but chips work if that’s what you have.
Marshmallow Fluff: Don’t replace the fluff with whole marshmallows; marshmallows will melt and sink into the dough, giving a sticky bottom layer and no distinct marshmallow center.
More S’mores Treats to Love:
- Easy S’mores Bars – graham cracker crust version
- Golden Graham S’mores Bars – a cereal-based twist on the classic
S’mores Cookie Bars
Equipment
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8×8 inch (20×20 cm) pan
Ingredients
- ¾ cup unsalted butter, melted and cooled slightly
- ½ cup brown sugar
- ¼ cup granulated sugar
- 1 large egg
- 1 large egg yolk, in addition to the whole egg
- 2 teaspoons vanilla extract
- 1½ cup all-purpose flour
- ¼ teaspoon salt
- ½ cup graham crumbs, about 5 sheets
- 2 XL Hershey’s milk chocolate bars, or about 1½ cups chocolate chips
- 1½ cups marshmallow fluff, about ½ of a 16 ounce container
Instructions
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Preheat the oven to 350°F (180°C). Line an 8×8 inch (20×20 cm) square pan with parchment, leaving an overhang for easy removal.
Make the Cookie Dough
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In a large bowl, whisk together the melted butter, brown sugar and granulated sugar until fully combined and the butter is no longer sitting on top.
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Whisk in the egg, extra yolk and vanilla until smooth.
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Mix in the flour and salt until no lumps remain, then stir in the graham crumbs until evenly distributed.
Assemble the Bars
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Scoop out 1 cup of dough and set aside for the top layer.
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Press the remaining dough into the prepared pan to form an even base.
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Arrange chocolate over the dough to create an even layer, or sprinkle chocolate chips evenly.
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Spread the marshmallow fluff over the chocolate in an even layer.
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Form the reserved dough into small dollops, flatten them into discs, and place them across the marshmallow to cover as much as possible while leaving a little showing.
Bake & Slice
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Bake on the middle rack for 30–35 minutes, until the top is golden and any exposed marshmallow has puffed slightly.
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Cool the bars in the pan. They’re still gooey after a few hours; for the cleanest slices, cool at least 8 hours.
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Lift the bars from the pan using the parchment overhang, place on a cutting board, and slice with a sharp knife.
Nutrition
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