Peanut Butter S’mores Brownies are chewy, crunchy, and perfectly sweet. The best combination of two favorite desserts in one place! A perfect dessert recipe for summer!

This post is sponsored on behalf of Karo® Syrup to create this recipe. I only partner with brands that I use in my kitchen. All opinions expressed are 100% my own.
You all know how excited I am for it to officially be S’MORES SEASON!! I mean, I was born on National S’mores Day (August 10th), so I might have a little skin in the game. But S’mores season (aka summer) is upon us and I am READY!
I have made and shared all sorts of s’mores inspired treats here, but today, with a little help from Karo® Syrup, I’ve made the mother of all s’mores. Actually it might be the mother of all brownies as well…because I’ve combined two favorites and put my own over the top spin on them both!
The brownie is fudgy and chocolatey, and the no-bake s’mores topping is a combination of peanut butter and graham cereal sweetened with Karo® Syrup, for the perfect amount of balance. I truly believe this is the way to “bake a little extra” and kick off your summer!

How to Make These S’mores Brownies
The brownie base is easy and packed with chocolate. If you would like to save some time and skip the homemade brownie recipe, you can certainly use your favorite boxed-brownie mix. I won’t be mad.
Once the brownies are done baking, sprinkle some mini marshmallows on top…
Pop them under the broiler so they get all warm and toasty…
Prepare your s’mores topping with graham cereal…
And mix that with Karo® Syrup, peanut butter and a little granulated sugar to make a perfectly sweet, crunchy topping.
And oh, I can’t forget the chocolate…these ARE s’mores…
The mixture will be a gooey, delicious mess of perfection.
Spread that on top of the brownies…
Sprinkle a few more chocolate chips on top for prosperity, and let it set up!
The crunchiness and perfectly sweetend topping from using Karo® Syrup paired with the brownies is a match made in dessert heaven!
Hope you enjoy these as much as I did!
Peanut Butter S’mores Brownies
- Prep Time: 15 minutes
- Cook Time: 50 mins
- Total Time: 50 mins
- Yield: 24 large brownies 1x
- Category: Brownies
- Method: Oven
- Cuisine: American
Description
Peanut Butter S’mores Brownies are chewy, crunchy, and perfectly sweet. The best combination of two favorite desserts in one place! A perfect dessert recipe for summer!
Ingredients
Brownies
- 1 cup semisweet chocolate chips
- 1 cup milk chocolate chips
- 1/2 cup butter
- 3/4 cup light brown sugar
- 3/4 cup granulated sugar
- 4 eggs
- 2 teaspoons vanilla
- 1/2 teaspoon kosher salt
- 1 cup flour
- 3 cups mini marshmallows
Peanut Butter S’mores layer
- 1 cup Karo® Syrup
- 1 cup granulated sugar
- 1 cup creamy peanut butter
- 5 cups honey graham cereal
- 1 cup semisweet chocolate chips, divided
Instructions
- Preheat the oven to 325°F. Line a 9×13- inch baking pan with foil, and coat with nonstick spray. Set aside.
- In a medium saucepan, combine the semisweet chips, milk chocolate chips, and butter and melt over medium-low heat, stirring constantly. Once the chocolate is melted, remove the pan from the heat immediately.
- Whisk both the sugars into the chocolate and add the eggs, one at a time, whisking constantly, until evenly combined. Next mix in the vanilla until smooth. Stir in the salt and flour until they’re evenly incorporated and pour the batter into the prepared pan.
- Bake the brownies for 35-40 minutes, until the center is set and a toothpick inserted 3 inches from the edge comes out clean. Remove from the oven, and turn the oven to broil.
- Immediately sprinkle the mini marshmallows on top of the brownies.
- Return the brownies back into the oven on the top shelf for 30 seconds – 1 minute, or until the marshmallows are lightly golden. Watch carefully as they will burn quickly.
- Allow the brownies to cool in the pan on a wire rack while you prepare the topping.
Peanut Butter S’mores Layer
- Cook the corn syrup and sugar together in a large saucepan over medium heat, stirring to dissolve the sugar. Bring the mixture to a boil. Remove from the heat. Stir in the peanut butter; mix well.
- Fold in the cereal, until coated. Then stir in3/4 cup of the semisweet chips. They will melt slightly, this is ok.
- Spread the mixture on top of the marshmallows, and sprinkle with the remaining chocolate chips.
- Allow the brownies to cool completely before cutting into bars.
Nutrition
- Serving Size: 1 brownie
- Calories: 376
- Sugar: 43.6 g
- Sodium: 204.6 mg
- Fat: 13.9 g
- Carbohydrates: 61.4 g
- Protein: 6 g
- Cholesterol: 0.5 mg
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Hi, I’m in the UK and really want to make these but can’t get karo syrup. Is there anything I could substitute?
I love all your yummy recipes but I hate all the advertising they come with, especially the non food related ads. Hate them and I avoid printing your recipes if the ads are there. Then if I don’t print them then I don’t make the recipe. Simple
aw man, that’s a shame. The ads, unfortunately, are what makes me able to run this website…so while I know they can sometimes be annoying, they are a necessary part of my business. BUT I feel like the best way to avoid the ads is to actually just go in and print the recipe so you don’t have to revisit the site for the recipe. The ads will always be there, so I hope you understand where I am coming from. Thanks so much and I truly appreciate your feedback!
Wow, these are dangerous! YUMMMM!
Is there a substitute for the Karo? I have literally everything else in my house …
May I ask what the corn syrup is for??
Absolutely LOVE the peanut butter s’mores brownie combo!
Holy cow these look amazing!!!!!! I would love to make them for a niece, however she is allergic to peanut butter, does anyone have any idea how I could make the topping without the peanut butter? So they would basically become s’more brownies?
you could use Cookie Butter or Biscoff spread!
Chewy, crunchy and sweet, three of my favorites in one. Love these!
YUM! These are amazing! Can’t wait to try them!
These are the brownies of my DREAMS! Is it wrong that I want to make these for dinner??