Fluffernutter Rice Krispie Bars are the ultimate treat for anyone who loves the classic combination of peanut butter and marshmallows. The bars are the perfect blend of crispy Rice Krispies cereal, creamy peanut butter, and gooey marshmallows. It’s a no-bake treat that is great for parties, potlucks, and other events, or just as a snack! I also have Fluffernutter Cookies, which are also irresistible!

Fluffernutter Rice Krispie Bars on a White Counter Cut into 9 Pieces and Slightly Spread Out.

What is a Fluffernutter?

A fluffernutter is a simple sandwich made with peanut butter and marshmallows. During World War I, Emma Curtis published the sandwich, calling it a Liberty Sandwich. The name was changed to a fluffernutter sandwich in the 1960s for marketing purposes. Whatever it’s called, I am hooked on the combination of peanut butter and marshmallows. In fact, besides these rice krispie bars and cookies, I also have Fluffernutter Bars and Fluffernutter Fudge.

Ingredients & Substitutions

Peanut Butter: Use your favorite brand of creamy peanut butter in these bars. If crunchy peanut butter is all you have on hand, or more your preference, you could use that instead.

Marshmallows: Grab a 16-ounce bag of mini marshmallows, or make your own homemade marshmallows to use! You will need about 8 cups. If you are using regular-sized marshmallows, cut them up into smaller pieces first.

Cereal: Look for Rice Krispies or any variety of crispy rice cereal or toasted rice cereal.

Marshmallow Fluff: For even more ooey-gooeyness in every bite of these bars, I added marshmallow fluff. Marshmallow fluff, or marshmallow creme, is a sweet and gooey spreadable concoction that tastes like marshmallows. If you don’t have any on hand, make your own!

Stack of Fluffernutter Rice Krispie Bars on a White Counter.

Can I Use a Different Sized Pan?

Sure! I love a thick rice krispie bar, so I made these in a 9×9-inch baking dish. You could certainly use a 9×13-inch dish, but the bars will be thinner. Or, for even thicker bars, try them in an 8×8-inch baking dish!

Hands Pulling Apart a Soft Fluffernutter Rice Krispie Bar.

How to Store Fluffernutter Rice Krispie Bars

Store fluffernutter rice krispie bars in an airtight container at room temperature. They will last up to 5 days, but I doubt they will be around that long!

Fluffernutter Rice Krispie Bars Set out on a White Counter with Marshmallows and Peanut Butter.

Fluffernutter Rice Krispie Bars

Prep Time 10 minutes
Resting Time 30 minutes
Total Time 40 minutes
Fluffernutter Rice Krispie Bars are the ultimate treat for anyone who loves the classic combination of peanut butter and marshmallows.



  • Spray a 9×9-inch baking dish with nonstick cooking spray. Set aside.
  • In a large pot over medium heat, melt butter and ¼ cup of peanut butter.
  • Add marshmallows, frequently stirring until melted. Once melted, remove from heat.
  • Spray a clean rubber spatula with nonstick spray to prevent sticking. Using the spatula, fold in the Rice Krispies cereal. Stir until well-coated.
  • To a microwave-safe bowl, add ¼ cup of peanut butter. Heat for 15-20 seconds or until pourable and creamy.
  • Gently fold the peanut butter and marshmallow fluff into the cereal mixture just until incorporated. Do not overmix. Transfer the mixture to the prepared baking dish, pressing it into an even layer.
  • Add the remaining peanut butter to the microwave-safe bowl. Heat it up for about 15-20 seconds. Drizzle over the top of the bars.
  • Allow the bars to cool to room temperature before cutting and serving.


Did you make this recipe?

Thank you for making my recipe! You took pictures, right? Well go ahead and post them on Instagram! Be sure to mention me @iambaker and use the hashtag #YouAreBaker.

What the Test Kitchen had to say about this recipe:


Peanut Butter fans are going to LOVE these bars. The classic rice krispie bar is taken to a whole new level with this recipe! This peanut butter marshmallow combo is going to be your new favorite!


This is the way to make a rice krispie treat! I LOVE anything peanut butter, and this did not disappoint. It is the softest, chewiest, most flavorful rice krispie bar EVER! In fact, I have learned that I might be the number one fluffernutter fan out there!


If you're in the mood for something sweet, try this. Rice krispies are one of my favorite snacks. It is even more awesome because its a Fluffernutter Rice Krispie! This is a fun way to make Rice Krispie treats interesting! You get that creamy peanut butter flavor. On top of that, it is soft and chewy from the marshmallows. Delicious!

Excellent! You know that time you are craving the perfect ooey gooey snack? This one is the bomb! This takes your average rice krispie treat to the next level! Check out our other fluffernutter cookies and bars!! We did it again!


I love the salty peanut butter in contrast to the soft sweet marshmallow. A perfect balance of salty and sweet!!

Share with your friends!

Categorized in: ,

Related Recipes

Meet Amanda Rettke

Amanda Rettke is the creator of I Am Baker, and the bestselling author of Surprise Inside Cakes: Amazing Cakes for Every Occasion – With a Little Something Extra Inside.Over the course of her 15+ year blogging adventure, she has been featured in and collaborated with the Food Network, New York Times, LA Times, Country Living Magazine, People Magazine, Epicurious, Brides, Romantic Homes, life:beautiful, Publishers Weekly, The Daily Mail, Star Tribune, The Globe and Mail, DailyCandy, YumSugar, The Knot, The Kitchn, and Parade, to name a few.

Reader Comments

  1. I’m a little confused. It says 1 16oz bag of marshmallows, about 8 cups. 16oz is only 2 cups????

    1. It is absolutely 8 cups of mini marshmallows, you can prove this when buy a bag and see for yourself. 🙂

  2. These sound delish! What about a topping of milk chocolate. I like rice crispie treatments coated on top with melted milk chocolate chips, yummy.

  3. Delicious! I also added in some peanut butter chips because I had some on hand that needed to be used. Might try adding in some choc. chips next time I make them as well.

Leave a Reply

Your email address will not be published. Required fields are marked *

Recipe Rating

This site uses Akismet to reduce spam. Learn how your comment data is processed.