My Peanut Butter S’mores Bars have a graham cracker infused peanut butter cookie base loaded with melty marshmallows and milk chocolate bar pieces. Ready in less than 45 minutes! Recipe includes a how-to video!
Peanut Butter S’mores Perfection
These peanut butter s’mores bars combine all the flavors of your favorite fireside treat with a soft peanut butter cookie dough base. They are a less messy, more flavorful hybrid that is even more irresistible than its inspiration. My recipe makes plenty to share (24 servings!), so it’s perfect for summer cookouts and get togethers.
As with my chocolate chip cookie bars and brookies, we will intentionally slightly under-bake these bars for soft and chewy results. I do this because the bars continue to cook as they cool, and baking the whole way through in the oven would make for hard, over-baked results. To ensure yours are ready, I recommend using a toothpick and looking for a few moist, fudgy crumbs (not wet batter) rather than waiting for it to be completely clean.
Why I love them:
- Subtle graham cracker flavor that complements the peanut butter perfectly 👌🏼
- Plenty of marshmallows that melt as they bake, creating gooey tunnels of chewy marshmallow goodness.
- Real Hershey bars for that authentic s’mores taste, with the option to substitute chocolate chips instead!
What You Need
Here are the key ingredients in my peanut butter s’mores bars:
- Peanut butter. Crunchy or creamy peanut butter will work in this recipe, but I don’t recommend using a natural peanut butter (the kind that separates). Substituting a natural peanut butter could result in too-dry, crumbly bars.
- Brown sugar. Either light or dark brown sugar will work here. If you don’t have any on hand, you can always make your own brown sugar.
- Mini marshmallows. Use the soft mini marshmallows (not the dehydrated kind that come in hot chocolate mix). These will create a lightly crisp, crackly top wherever they touch the surface of your cookie bars. The look is a bit messy, but totally delicious (and on-par with traditional s’mores with the messiness factor).
- Cornstarch. I love sneaking some cornstarch into my cookies and cookie bars; it keeps them soft and tender without drying them out like extra flour could do.
- Chocolate. Sure, you could use milk chocolate chips, but real s’mores flavor calls for real s’mores ingredients, so I like to use broken up Hershey bars. I save one bar for breaking up and pressing into the tops of my bars after they come out of the oven; this is optional, but makes the bars extra pretty!
SAM’S TIP: This batter is thick! In fact, it’s so thick that I actually broke one of my favorite spatulas trying to stir in the marshmallows and chocolate. The milk does help thin it out a bit, but just be aware that it’s going to take a little muscle to incorporate the add-ins!
Remember, this is just an overview of the ingredients I used and why. For the full recipe please scroll down to the bottom of the post!
How to Make Peanut Butter S’mores Bars
- Combine the wet ingredients – Cream together the butter, peanut butter, and sugars until well combined. Stir in the eggs and vanilla.
- Fold in the dry ingredients – Combine the dry ingredients in a separate bowl, then gradually add them to the wet.
- Add the mix-ins – Stir in the milk, then fold in the chocolate bar pieces and mini marshmallows. The batter will be very thick!
- Bake – Spread into a parchment lined pan and bake for 25-28 minutes at 350F. Let cool before cutting and serving.
SAM’S TIP: I recommend baking these bars in a metal pan simply because that’s what I’ve used and tested. A glass pan will work, but your cookie bars will take longer to finish baking this way.
Frequently Asked Questions
This recipe is made with a peanut butter cookie base, so removing the peanut butter could cause issues. Instead, I’d recommend making the dough for my s’mores cookies and following the baking instructions listed here.
Your peanut butter s’mores bars will last for about a week at room temperature in an airtight container.
These are very thick cookie bars, a smaller baking pan would yield extraordinarily thick bars that would be difficult to cook all the way through and would take a long time to bake. I’m not saying it can’t be done, I’m just saying it’s not my preference. You could, however, cut the recipe in half and bake for less time, your bars will be thinner this way.
Graham crackers, chocolate, marshmallows, and peanut butter…can you think of a better combination? 🤤
Let’s bake together! I’ll be walking you through all the steps in my written recipe and video below! If you try this recipe, be sure to tag me on Instagram, and you can also find me on YouTube and Facebook
Peanut Butter S’mores Bars
- 1 cup (227 g) unsalted butter softened
- 1 cup (235 g) creamy peanut butter I don't recommend using natural peanut butter
- 1 cup (200 g) light or dark brown sugar tightly packed
- 1 cup (200 g) granulated sugar
- 1 large egg + 1 large egg yolk
- 1 ½ teaspoons vanilla extract
- 2¾ cups (345 g) all-purpose flour
- ½ cup (65 g) graham cracker crumbs
- 1 teaspoon baking powder
- 1 teaspoon cornstarch
- ½ teaspoon salt
- 2 Tablespoons milk
- 7 1.55 oz milk chocolate Hershey bars chopped into pieces* or 2 cups milk chocolate chips (340g)
- 1 ½ cups (72 g) mini marshmallows
- Preheat oven to 350F (175C) and line a 13×9 metal pan with parchment paper or grease and flour the sides and bottom of the pan.
- Combine butter, peanut butter, and sugar in a large bowl and use an electric mixer to beat until light, creamy and well-combined.1 cup (227 g) unsalted butter, 1 cup (235 g) creamy peanut butter, 1 cup (200 g) light or dark brown sugar, 1 cup (200 g) granulated sugar
- Add egg/egg yolk and vanilla extract, and stir well.1 large egg + 1 large egg yolk, 1 ½ teaspoons vanilla extract
- In a separate bowl, whisk together flour, graham cracker crumbs, baking powder, cornstarch, and salt.2¾ cups (345 g) all-purpose flour, ½ cup (65 g) graham cracker crumbs, 1 teaspoon baking powder, 1 teaspoon cornstarch, ½ teaspoon salt
- Gradually, on low speed, add flour mixture to peanut butter mixture, pausing occasionally to scrape down sides of bowl.
- Add milk and stir until combined.2 Tablespoons milk
- Fold in chopped Hershey bars and mini marshmallows — the batter will be thick (I broke a spatula stirring it so proceed with caution!).7 1.55 oz milk chocolate Hershey bars, 1 ½ cups (72 g) mini marshmallows
- Spread batter into prepared ban and bake on 350F (175C) for 25-28 minutes (toothpick inserted in center should come back mostly clean with only a few crumbs)
- Allow to cool completely before cutting and serving.
Nutritional information is based on third-party calculations and should be considered an estimate only. Actual nutritional content will vary based upon brands used, measuring methods, cooking method, portion sizes, and more.
Originally published August 20, 2018
Sarah Eden Walker
I think there might be a typo on your flour amount. 1 3/4 cup is NOT 345 grams. I went with the weight as that made more sense to me (since you said they were thick). They are in the oven now, and I can’t wait to try them!
Hi Sarah! I’m so sorry for the confusion! You are correct! It should read 2 3/4 cup of flour. I actually re-tested the recipe today to make sure the grams were correct (and they were). I have updated the post. Thank you so much for catching that. I hope you loved them! 🙂
Sarah Eden Walker
They were a huge hit!
This looks like an amazing recipe that I know my family will love! One question: could I use chocolate chips instead of broken Hershey bars and still have good results? I have lots left over from Christmas and would like to use them up. Love your recipes always a hit!
Emily @ Sugar Spun Run
You sure can, Alison 😊 Enjoy!
This turned out GREAT but I definitely needed to bake it so much longer then listed. So I did that the second time I made these. The first time they were underdone in the center, but some people like that.
Not sure why it’s taking so long to bake? I use NordicWare 9X13 pan that I line with parchment. I only use this blog for all of my recipes…the one thing is that I cannot find mini marshmallows as in the type that you’ll find in hot cocoa packets which is the size that looks like is used in the pictures. I can only find the mini marshmallows that you’d add to your hot cocoa (like 1/4 of a traditional marshmallow) Wondering if that makes a bit of a difference since those are gooey-er in nature?
The bigger marshmallows could be causing them to be gooey-er for sure. It can be tough to find those mini dehydrated marshmallows. I can normally find them near the hot chocolate. I’m not sure why yours are taking longer to bake, but I’m glad you’ve got it figured out. 🙂
hi, how do we store this and how long does it last?
These will last for about a week at room temperature in an air tight container. 🙂
I want to start by saying I never comment on recipes, ever. I bake all the time, and have tried literally hundreds of recipes from Pinterest. I have to say there are no words to describe how delicious and easy these bars are. I made them for a coworker’s birthday, and will be making them again…and again…
Thank you so much, Trish! I appreciate you taking the time to leave a comment. I’m so glad you enjoyed them so much. 🙂
Hi Sam, wanted to ask if it’s okay to not incorporate the peanut butter in this recipe, my daughter is allergic. Is there a similar recipe and will it come out okay if I don’t use it? Thanks!
Sugar Spun Run
Hi, Maricela! This recipe is a peanut butter cookies base so I do not reccomend it. I have a S’mores Cookies recipe that I would use instead. You can bake the dough into cookies or into cookie bars if you’d prefer. There is no peanut butter in that recipe. 🙂
sooo delicious can not stop eating it ,i made them for a project but i ate sooo much it remained only 2 but i got an A instead of an A* ,bummer,but i am still obsessed with it.*^_^*
😂 I’m so glad you enjoyed them! 🙂
Joanne J Woodman
Sam,wow I made these for work. They couldn’t eat them fast enough. Great recipe. Thanks Joanne
I am so glad everyone enjoyed them Joanne! Sounds like you’ll be the new favorite at work! 😉
Just wondering, why not use natural peanut butter?
Can’t wait to try making these!
It could make them come out dry and crumbly.
I am already a subscriber but do not have the cookie e-book.
Hi Adelaide! I’m not sure why you didn’t get it when you subscribed, but I just e-mailed you the e-book!