The only thing better than s’mores might be these peanut butter s’mores bars. Chewy peanut butter graham cookie dough surrounds a layer of milk chocolate, more peanut butter and gooey marshmallow in the center. Simple to make, these bars are the perfect mash-up of peanut butter and classic s’mores flavors.
These peanut butter s’mores bars are a variation on traditional s’mores cookie bars. The base is a chewy peanut butter cookie dough where part of the flour is replaced with graham crumbs to recreate that familiar campfire flavor. The center is made of a thick layer of milk chocolate, a smear of peanut butter and a generous amount of marshmallow fluff. The peanut butter graham cookie dough acts as the graham cracker element in a regular s’more, giving the bars a rich, toasty taste and tender chew.
Making Peanut Butter S’mores Bars
Start by preparing the peanut butter graham cookie dough. No mixer is required — just a few simple whisking and stirring steps. Combine melted butter, smooth peanut butter and brown sugar until smooth, then whisk in a whole egg, an extra egg yolk and vanilla extract. Stir the flour and salt into the wet mixture until no lumps remain, then fold in the graham crumbs for that signature flavor and texture.
Assemble and bake the bars following these steps:
- Scoop out about 1 cup of the cookie dough and set it aside for the top layer.
- Press the remaining dough into the bottom of a lined 8×8 inch pan, making an even base.
- Place a layer of milk chocolate over the cookie dough, pressing down gently so it adheres. Whole chocolate bars or chopped chocolate chips both work.
- Microwave the peanut butter briefly (about 30–45 seconds on medium), stir until smooth, and spread it over the chocolate layer for an even, spreadable filling.
- Warm the marshmallow fluff briefly in the microwave (about 30–45 seconds) so it becomes easier to spread, then spoon it over the peanut butter layer.
- Form the reserved cup of cookie dough into flat discs and arrange them over the marshmallow layer. Try to cover most of the marshmallow but it’s fine if some shows through — exposed fluff will puff up during baking and create delightful pockets of goo.
- Bake in a preheated oven for about 30–35 minutes, or until the top is set and golden. The exposed marshmallow will puff where visible and the peanut butter cookie topping will turn golden brown.
Recipe Tip
For clean, neat slices let the bars cool completely — ideally at least 8 hours. If you cut them while warm they’ll be very gooey and may fall apart; waiting allows the layers to set. I waited about 4 hours for the photos and they were still slightly gooey but held together well without needing a spoon.
An Important Note About Marshmallow Fluff
Use marshmallow fluff (marshmallow creme) for this recipe — do not substitute with regular marshmallows. Regular marshmallows will melt during the long bake and sink into the cookie layers, leaving you without the distinct marshmallow layer in the middle. Marshmallow fluff holds its texture and gives you that signature gooey center.
More S’Mores Treats to Love
- Easy S’mores Bars — a graham crust with a thick chocolate layer and toasted marshmallows on top
- Golden Graham S’mores Bars
- S’mores Cookie Bars
Peanut Butter S’mores Bars
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Equipment
-
8×8 inch (20×20 cm) pan
Ingredients
Peanut Butter Graham Cookie Dough
- ½ cup unsalted butter (112 grams), melted
- ¼ cup smooth peanut butter (about 65 grams)
- ¾ cup brown sugar (158 grams)
- 1 large egg
- 1 large egg yolk (in addition to the whole egg)
- 1 teaspoon vanilla extract
- 1½ cup all-purpose flour (188 grams)
- ¼ teaspoon salt
- ½ cup graham crumbs (about 50–60 grams, ~4–5 sheets)
Filling Ingredients
- 2 XL Hershey’s milk chocolate bars (or 1½ cups chocolate chips)
- ½ cup smooth peanut butter (about 130 grams)
- 1¼ – 1½ cups marshmallow fluff (marshmallow creme)
Instructions
- Preheat the oven to 350°F (180°C). Line an 8×8 inch (20×20 cm) square pan with parchment paper, leaving an overhang.
Make the Peanut Butter Graham Cookie Dough
- In a medium bowl whisk together the melted butter, peanut butter and brown sugar until smooth and lump-free.
- Add the egg, extra yolk and vanilla; whisk until fully incorporated and no egg pieces remain.
- Stir in the flour and salt until there are no lumps of flour, then fold in the graham crumbs.
Assemble & Bake
- Scoop out about 1 cup of dough and reserve it for the top layer.
- Press the remaining dough into the prepared pan to form an even base.
- Place chocolate over the dough, breaking bars as needed to cover the surface, and press down slightly.
- Warm the peanut butter in a heatproof bowl for 30–45 seconds, stir until smooth and spread over the chocolate layer.
- Warm the marshmallow fluff for 30–45 seconds, then spread it over the peanut butter to create an even layer.
- Shape the reserved cookie dough into flat discs and arrange them over the marshmallow, covering most of the surface but allowing some fluff to peek through if desired.
- Bake in the middle of the oven for about 30–35 minutes, until the top cookie layer is set and golden and any exposed marshmallow has puffed.
- Cool the bars completely in the pan. For clean slices, lift them out using the parchment overhang and cut with a sharp knife once fully cooled. Warm bars will be very gooey and may need to be eaten with a spoon.
Notes
- Peanut Butter: Use smooth peanut butter that doesn’t separate; oil-separated peanut butter can lead to inconsistent texture.
- Marshmallow Fluff: This recipe requires marshmallow fluff or marshmallow creme. Do not use regular marshmallows; they will melt into the cookie layer.
- Chocolate Bars: Bar sizes vary by country. If you want full coverage, you may need to adjust the number of bars or use chocolate chips.
- Nutrition: Nutrition info is an estimate per slice if the pan is cut into 12 bars.
- Storage: Store in an airtight container at room temperature for up to 5 days.
Nutrition
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