I can’t get over these peanut butter s’mores bars, with chewy browned butter blondie, gooey marshmallow, melty chocolate, and rich peanut butter in every bite. They’re the kind of dangerously delicious summer dessert that disappears fast.

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I’m obsessed with these Peanut Butter S’mores Bars because they hit that messy, sweet-salty, summer-dessert spot without asking me to choose between cookie bars and campfire candy. I love the way creamy peanut butter cuts through all that sugar and makes every bite feel richer, louder, more impossible to quit.

And the mini marshmallows? Total chaos in the best way.

Chewy edges, gooey pockets, that sticky pull I absolutely chase. But what really gets me is how dangerous they are on the counter.

One square turns into three. No regrets.

Just a pan of bars I keep coming back to.

Ingredients

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Browned butter brings that nutty, toasty flavor that makes everything taste bakery-level.
Brown sugar keeps the bars soft, chewy, and a little caramel-like.
Granulated sugar adds sweetness and helps the edges get lightly crisp.
Eggs hold everything together, so you’re not eating sweet crumbs.
Vanilla makes the whole thing smell warm, cozy, and kind of nostalgic.
Flour gives the bars structure without making them feel too cakey.
Peanut butter adds salty-sweet richness, plus it makes these extra satisfying.
Chocolate chips melt into gooey pockets, which is basically the best part.
Mini marshmallows get soft, sticky, and perfectly s’mores-like.
Graham cracker crumbs bring that campfire crunch without needing a fire.
Flaky sea salt cuts the sweetness, and you’ll be glad it’s there.

Ingredient Quantities

1/2 cup (113 g) unsalted butter, browned and cooled

1 cup (200 g) packed light brown sugar

1/4 cup (50 g) granulated sugar

2 large eggs, room temperature

1 teaspoon vanilla extract

1 1/2 cups (190 g) all purpose flour

1 teaspoon baking powder

1/2 teaspoon fine salt

1/2 cup (128 g) creamy peanut butter

1 cup (175 g) semisweet chocolate chips

1 1/2 cups (90 g) mini marshmallows

1 cup (100 g) graham cracker crumbs, about 8 sheets crushed

Flaky sea salt for sprinkling, optional

How to Make this

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1. Preheat oven to 350 F and line an 8-inch square baking pan with parchment leaving an overhang for easy removal; lightly grease parchment.

2. In a medium bowl whisk together 1 1/2 cups (190 g) all purpose flour, 1 teaspoon baking powder and 1/2 teaspoon fine salt; set aside.

3. In a large bowl whisk 1/2 cup (113 g) cooled browned butter, 1 cup (200 g) packed light brown sugar and 1/4 cup (50 g) granulated sugar until smooth and slightly glossy.

4. Add 2 large room temperature eggs, one at a time, whisking until combined, then whisk in 1 teaspoon vanilla extract and 1/2 cup (128 g) creamy peanut butter until the batter is uniform.

5. Fold the dry ingredients into the wet mixture just until combined, scraping the bowl so there are no streaks of flour.

6. Stir in 1 cup (175 g) semisweet chocolate chips and 1 cup (100 g) graham cracker crumbs until evenly distributed.

7. Spread the batter into the prepared pan in an even layer, smoothing the top with a spatula.

8. Scatter 1 1/2 cups (90 g) mini marshmallows evenly over the batter and press them lightly into the surface.

9. Bake 20 to 25 minutes until the edges are golden and the center is set but still slightly soft. Cool completely in the pan on a wire rack, then lift out with the parchment, cut into bars and sprinkle with flaky sea salt if desired.

Equipment Needed

1. 8-inch square baking pan
2. Parchment paper
3. Saucepan or small skillet for browning butter
4. Large mixing bowl and medium mixing bowl
5. Whisk
6. Rubber or silicone spatula
7. Measuring cups and spoons and a kitchen scale
8. Baking sheet or wire rack for cooling
9. Food processor or rolling pin and zip bag for crushing graham crackers
10. Oven mitts and a sharp knife for cutting bars

FAQ

Can I use regular melted butter instead of browned butter? Yes. Browned butter adds a toasty, nutty note but ordinary melted and cooled unsalted butter will work fine and keep texture the same.

How should I store the bars and how long do they keep? Store cooled bars in an airtight container at room temperature for up to 3 days or in the refrigerator for up to 7 days. Warm to room temperature or microwave briefly before serving if chilled.

Can I make these gluten free? You can substitute a 1-to-1 gluten free all purpose flour blend for the flour. Check that the blend contains xanthan gum or add 1/4 teaspoon if your blend is gum free.

Will the marshmallows melt away during baking? Mini marshmallows will soften and brown on top but should retain some chew. For less melting, fold most marshmallows into the batter and reserve a handful to sprinkle on top near the end of baking.

Can I swap crunchy peanut butter or another nut butter? Crunchy peanut butter will change the texture with bits of nuts but works. Almond or cashew butter can be used but expect a different flavor and possibly slightly different spreading behavior.

Any tips for getting even slices and preventing soggy bars? Let the bars cool completely in the pan, then chill for 30 to 60 minutes before slicing for cleaner edges. Use a sharp knife warmed under hot water and wiped dry between cuts for neat squares.

Peanut Butter S’mores Bars Recipe Substitutions and Variations

Unsalted butter, browned and cooled: use regular melted unsalted butter (same weight) if you skip browning; for dairy free swap equal weight refined coconut oil or vegan butter.
Creamy peanut butter: swap almond butter or cashew butter 1:1 for similar texture and flavor; for a nut free option use sunflower seed butter (SunButter) 1:1.
All purpose flour: use a 1:1 gluten free all purpose flour blend (ensure it contains xanthan gum or add 1/4 teaspoon per cup) for a gluten free version.
Mini marshmallows: substitute 1 cup marshmallow creme or about 8 large marshmallows chopped to roughly equal volume; note texture will be slightly different when baked.

Pro Tips

1. Brown the butter slowly and watch it closely. Once the foam settles and the milk solids turn golden brown, take it off the heat right away and cool to just-warm. That nutty aroma is the goal, but if it keeps cooking it will taste bitter.

2. Bring the eggs to room temperature and whisk them in one at a time. Room temperature eggs incorporate more easily, giving a smoother batter and better rise. If your eggs are cold, pop them in warm water for 5 minutes.

3. Fold the dry ingredients in gently and stop as soon as the streaks of flour disappear. Overmixing will give chewy, dense bars instead of tender ones. Scrape the bowl well so there are no hidden pockets of flour.

4. Lightly press the marshmallows into the batter so they stick, but avoid burying them. If you want a toasted finish, run the bars under a hot broiler for 20 to 30 seconds or use a kitchen torch briefly, watching constantly so they do not burn.

5. Cool completely before slicing. These bars firm up as they cool, making cleaner cuts. For neater slices, chill for 20 to 30 minutes, use a sharp knife warmed under hot water and wiped dry between cuts, and sprinkle flaky sea salt just before serving.

Peanut Butter S'mores Bars Recipe

Recipe by Tina Bueller

0.0 from 0 votes

Servings

servings

Calories

415

kcal

Equipment: 1. 8-inch square baking pan
2. Parchment paper
3. Saucepan or small skillet for browning butter
4. Large mixing bowl and medium mixing bowl
5. Whisk
6. Rubber or silicone spatula
7. Measuring cups and spoons and a kitchen scale
8. Baking sheet or wire rack for cooling
9. Food processor or rolling pin and zip bag for crushing graham crackers
10. Oven mitts and a sharp knife for cutting bars

Ingredients

1/2 cup (113 g) unsalted butter, browned and cooled
1 cup (200 g) packed light brown sugar
1/4 cup (50 g) granulated sugar
2 large eggs, room temperature
1 teaspoon vanilla extract
1 1/2 cups (190 g) all purpose flour
1 teaspoon baking powder
1/2 teaspoon fine salt
1/2 cup (128 g) creamy peanut butter
1 cup (175 g) semisweet chocolate chips
1 1/2 cups (90 g) mini marshmallows
1 cup (100 g) graham cracker crumbs, about 8 sheets crushed
Flaky sea salt for sprinkling, optional

Directions

Preheat oven to 350 F and line an 8-inch square baking pan with parchment leaving an overhang for easy removal; lightly grease parchment.
In a medium bowl whisk together 1 1/2 cups (190 g) all purpose flour, 1 teaspoon baking powder and 1/2 teaspoon fine salt; set aside.
In a large bowl whisk 1/2 cup (113 g) cooled browned butter, 1 cup (200 g) packed light brown sugar and 1/4 cup (50 g) granulated sugar until smooth and slightly glossy.
Add 2 large room temperature eggs, one at a time, whisking until combined, then whisk in 1 teaspoon vanilla extract and 1/2 cup (128 g) creamy peanut butter until the batter is uniform.
Fold the dry ingredients into the wet mixture just until combined, scraping the bowl so there are no streaks of flour.
Stir in 1 cup (175 g) semisweet chocolate chips and 1 cup (100 g) graham cracker crumbs until evenly distributed.
Spread the batter into the prepared pan in an even layer, smoothing the top with a spatula.
Scatter 1 1/2 cups (90 g) mini marshmallows evenly over the batter and press them lightly into the surface.
Bake 20 to 25 minutes until the edges are golden and the center is set but still slightly soft. Cool completely in the pan on a wire rack, then lift out with the parchment, cut into bars and sprinkle with flaky sea salt if desired.

Notes

Below you’ll find my best estimate of this recipe’s nutrition facts. Treat the numbers as a guide rather than a rule—great food should nourish both body and spirit. Figures are approximate, and the website owner assumes no liability for any inaccuracies in this recipe.