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Peanut Butter Rice Krispie Brownies

These Peanut Butter Rice Krispie Brownies are the perfect sweet treat! Rich brownies topped with marshmallow and peanut butter chocolate Krispie treats.

Peanut Butter Marshmallow Krispie Topped Brownies cut on a plate.

If you’re looking for the PERFECT brownie bar cookie dessert recipe, I have you covered! 

These peanut butter Rice Krispie brownies are sweet, full of chocolate flavor, and super simple to throw together. 

They are made super easy by box brownies, but you could easily substitute your favorite homemade brownie. 

The topping brings a big bite of texture, and the addition of peanut butter gives it that classic chocolate-peanut butter combo. 

Oh, and then I threw in some marshmallows to bring in a whole s’mores vibe. 

It’s a flavor party in your mouth. 

Plus, it’s a great potluck dessert because a little goes a long way in this decadent treat!

Peanut Butter Marshmallow Krispie Topped Brownies cute on a white plate.

Rice Krispie brownies ingredients

  • Boxed brownie mix
  • Mini marshmallows
  • Semi-sweet chocolate chips
  • Peanut butter
  • Unsalted butter
  • Rice Krispie cereal

How to make layered brownies

Making these peanut butter marshmallow krispie-topped brownies is so easy!

  1. Cook your brownies according to the box directions.
  2. Before your brownies are fully cooked, top with marshmallows and let them melt in the oven.
  3. Let the brownies cool.
  4. Melt chocolate, peanut butter, and butter.
  5. Stir in cereal until combined.
  6. Take the cereal mixture and spread over the cooled brownies.
  7. Let it set up in the fridge for at least 2 hours and then cut.
Peanut Butter Marshmallow Krispie Topped Brownies sliced to show the layers.

Leaving out the peanut butter

You can leave out the peanut butter, but it will change the texture of the chocolate Krispie topping. 

The peanut butter not only brings flavor but also helps bring in a little fat to the chocolate, so it sets up firmly without becoming too hard. 

If you cannot have peanut butter, I suggest swapping it out with Nutella or any other type of nut butter. 

Using a different nut butter

If you read the above, you’ll know you can use nut butter!

You can easily substitute almond, cashew, or even hazelnut butter. 

Seriously, any nut butter you have on hand.

I have not tried sunflower seed butter, but I think it would work fine here, too. 

Using a different cereal

Much like leaving out the peanut butter, changing the cereal will change the texture of the brownies. 

They make several kinds of puffed brown rice cereal if you’re looking for a healthier alternative to Rice Krispies. They are typically found in the natural section of the grocery store. 

Also, using generic rice cereal in this recipe works out perfectly well! 

Other great options would be lightly crushed rice Chex or cornflakes. 

If you want extra chocolate, try subbing in Cocoa Krispies or Cocoa Pebbles!

Peanut Butter Marshmallow Krispie Topped Brownies on a plate with a fork.

Cutting the recipe in half

You can bake the boxed brownies in a 9×9 pan instead of a 9×14 pan. The brownies will be thicker, but you only need to cover half as much.  

Just make sure to use a boxed brownie that can be baked in a 9×9 or an 8×8 pan. Some brownie mixes are specifically made for baking in a smaller pan. My favorite is the Ghirardelli boxed brownies!

Or, sometimes, you can find smaller-sized brownie mixes in pouches. They are usually in the same area as the ready-to-mix cookies. 

If you cook in a 9×9, you will cut the topping ingredients by half. 

Peanut Butter Marshmallow Krispie Topped Brownies served on a plate.

Storing these brownies

These brownies will be covered on the counter for 2-3 days.

However, the chocolate topping could become soft and melty if it’s warm in your house. 

If your home is warmer, I suggest covering the pan with plastic wrap or foil and keeping it in the fridge. 

The brownies may be stiff when you first take them out, but they will soften quickly.

Peanut Butter Marshmallow Krispie Topped Brownies stacked on top of each other.

More easy marshmallow desserts

Try a few of my other delicious desserts!

ow Krispie topped brownies stacked on a white cake plate

Peanut Butter Rice Krispie Brownies

These Peanut Butter Rice Krispie Brownies are the perfect sweet treat! Rich brownies topped with marshmallow and peanut butter chocolate Krispie treats.
4.58 from 26 votes
Print Pin
Prep Time 10 minutes
Cook Time 30 minutes
Additional Time 2 hours
Total Time 2 hours 40 minutes
Servings 16 servings




  • Preheat oven to temperature directed on brownie package.
  • Line a 9×13 pan with parchment paper.
  • Prepare brownies according to box directions.
  • 4 minutes before the brownies are fully cooked, pull brownies from the oven, and add marshmallows on the top.
  • Return to oven for 4 minutes to soften marshmallows.
  • Remove from oven and spread marshmallows over the top of brownies. Let cool completely.
  • In a microwave-safe bowl combine chocolate chips, peanut butter, and butter.
  • Heat on high for 30 seconds.
  • Stir and repeat until chocolate is melted and the mixture is smooth.
  • Add cereal and stir to combine.
  • Drop spoonfuls of chocolate mixture over the marshmallow layer, spreading as evenly as possible.
  • Put the brownies in the refrigerator for at least 2 hours to chill.
  • Lift from pan and cut into squares.



  • Do not cut the brownies before the topping has set up. They will not hold together properly, resulting in a sticky mess.
  • Use whatever brownie mix is your favorite. 
  • Brownie mixes can vary in size, but you want something around 18 ounces. Anything from 17-20 ounces will work. 
  • Lining the pan with parchment paper will help you life the brownies out of the pan and make it easier to cut and not stick. 


Serving: 1g | Calories: 251kcal | Carbohydrates: 24g | Protein: 5g | Fat: 16g | Saturated Fat: 6g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 6g | Trans Fat: 0.1g | Cholesterol: 7mg | Sodium: 81mg | Potassium: 180mg | Fiber: 2g | Sugar: 14g | Vitamin A: 73IU | Calcium: 18mg | Iron: 1mg
Course Dessert
Cuisine American
Keyword boxed brownie recipe, layered brownies, marshmallow brownies, peanut butter brownies, rice krispie treat recipe
Did you try this recipe?Leave a comment and 5 star review!
Peanut Butter Marshmallow Krispie Topped Brownies pin for Pinterest.

About Brandy!

I am a food lover and recipe developer bringing you delicious recipes that taste great and are easy to make! My food is inspired by travels around the world and my love of flavorful food. A list of things that make me happy: cats, Coke Zero, houseplants, and travel. Read more...

Recipe Rating


Friday 14th of October 2022

These are so scrumptious and delicious. Thankyou for sharing this recipe. A whole plate of candy bars. My favorite is the marshmallow goodness, with crispness of the chocolatey, peanut butter mixture on top. So easy to make.

Kathy B

Monday 6th of May 2019

You say to chill in the refrigerator for "a few hours" to chill. About how long did it take until they were set enough to cut?

Tweet birds mommy

Wednesday 23rd of August 2017

I have to make these! I don't have the rice Krispies though so I'll try it with fruity pebbles. ☺


Wednesday 7th of October 2009

Do you have to have peanut butter


Saturday 25th of July 2009

A combination of my favorite ingredients. Most important CHOCOLATE.


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