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