Fluffernutter Bars

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5 from 2 votes

Perfectly chewy peanut butter blondies are topped with sky-high, homemade marshmallow fluff! Next time try my fan favorite fluffernutter cookies or fluffernutter rice krispie treats.

Fluffernutter bars: peanut butter blondies topped with homemade marshmallow fluff

These fluffernutter bars were born from a craving for peanut butter and fluff. I would have just made a sandwich, but I was stuck at home during one of our bagillion nor'easters this year and we ran out.

I KNOW. Cardinal rule of an upcoming storm: cause a stampede at the grocery store and buy all the milk and bread, even if you don't eat bread or need milk. Me? I stock up on wine and chocolate. Priorities.

Peanut butter blondie bars

So then I was going to make my fan favorite fluffernutter cookies, but I wanted more fluff. I finally decided that I would try my hand at peanut butter bars and go from there.

Thankfully, that experiment went pretty damn well because the bars came out exactly the way I wanted them to! Soft, but not cakey. Chewy, but not overly dense. And most importantly, full of peanut buttery flavor.

I have this habit of cutting off the edges of brownies and bars while they're cooling, and I do it for two reasons: to taste test and to even out the bars themselves. You know how you end up with curved corner pieces and something the edges will be raised on the perimeter?

Yeah, I just cut those off and eat them. Everything is evened out and I get a snack. Win win.

Peanut butter blondie bars

While the bars cooled, I did some online searching for marshmallow frostings. I didn't have any jars of Fluff on hand (which is actually kind of shocking), so I needed to make my own.

My plan was to reuse the recipe for my s'mores cupcakes which is perfectly delicious, but I didn't have enough granulated since the bars themselves used up what I had around the house.

Guys… being stuck inside during nor'easters is the worst.

Rather than trying to reinvent the wheel and potentially wasting ingredients on failed batches, I went with this marshmallow recipe from Deliciously Organic.

It's even paleo if you want to use it for other recipes that you want to be 100% paleo! Because this recipe? This is most definitely not paleo.

We're using butter and sugars and peanut butter, which on its own isn't paleo because peanuts aren't nuts, they're legumes – and those are off limits for a paleo diet.

Did you know that? I didn't, until I really got into paleo baking and cooking. If you didn't know that either, consider this your fun fact of the day! You're welcome. 

Homemade marshmallow fluff

Okay, so about that marshmallow frosting… it's perfect for this.

It's stiff enough that you can layer it sky high on top of the peanut butter bars, which is of course what I did.

Fluffernutter bars: peanut butter blondies topped with homemade marshmallow fluff

If you want a thinner layer, that's fine, too… I suppose. You could make two batches of bars to frost with it, or you can store it in an airtight container in the fridge.

When you want to use it again, just whip it back into shape (it will separate as it settles).

Fluffernutter bars: peanut butter blondies topped with homemade marshmallow fluff

The combination of this frosting and these bars are fluffernutter perfection. I love it so much. 

The bars can easily stand on their own though – so if you wanted to leave them naked, you'll be just fine. Or you could top them with something else – maybe my mascarpone whipped cream, or cookie butter frosting, or just a hearty drizzle of dark chocolate. You really can't go wrong.

Still not enough fluffernutter fun for you? Try these fluffernutter cupcakes from my girl Lauren. You won't regret it, I promise.

Fluffernutter bars: peanut butter blondies topped with homemade marshmallow fluff

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Fluffernutter Bars

5 from 2 votes
Perfectly chewy peanut butter blondies are topped with sky-high, homemade marshmallow fluff!
Prep Time: 15 minutes
Cook Time: 30 minutes
Total Time: 45 minutes
Servings: 24 bars


Peanut butter bar layer

Fluff layer


Peanut butter bar layer

  • Preheat the oven to 350°F and line a 9×13 inch pan with parchment paper. Set aside.
  • In a large bowl, use a hand mixer to beat together butter, brown sugar and granulated sugar together until combined.
    1/3 cup (75 ⅔ g) unsalted butter
    3/4 cup (165 g) brown sugar
    1/2 cup (100 g) granulated sugar
  • Add in the peanut butter, eggs, and vanilla and beat to combine.
    1/2 cup (129 g) creamy peanut butter
    2 eggs
    1 teaspoon pure vanilla extract
  • Use a spatula to fold in the flour, baking powder, and salt.
    1 cup (125 g) all-purpose flour
    1 teaspoon baking powder
    1/2 teaspoon (½ teaspoon) salt
  • Spread evenly into prepared pan and bake for 28-30 minutes, or until a toothpick inserted into the center comes out with a moist crumb.
  • Let cook in pan for 5 minutes and then lift out and let cool completely on a wire rack.

Fluff layer

  • Place the egg whites and cream of tartar in the bowl of a stand mixer (aff link) fitted with a whisk attachment and whip the egg whites to soft peaks on medium speed.
    2 large egg whites
    1/4 teaspoon (¼ teaspoon) cream of tartar
  • At the same time, place maple syrup and salt in a medium sauce pan and bring to a boil over high heat. Continue boiling until the mixture reaches 240°F on a thermometer.
    1 1/4 cups (402 ½ g) pure maple syrup
    1/8 teaspoon (⅛ teaspoon) salt
  • When the syrup reaches 240°F, reduce the mixer speed to low and slowly add vanilla. Increase the speed to medium-high and whip for about 7 minutes – the marshmallow crème is stiff and glossy.
    2 teaspoons pure vanilla extract
  • Add the vanilla and whip an additional 2 minutes.
  • Frost cooled peanut butter bars, cut into 24 bars and enjoy!


Cover and store leftover bars at room temperature for up to a week.

Nutrition Facts

Calories: 169kcal | Carbohydrates: 27g | Protein: 3g | Fat: 6g | Saturated Fat: 2g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 2g | Trans Fat: 1g | Cholesterol: 20mg | Sodium: 116mg | Potassium: 103mg | Fiber: 1g | Sugar: 21g | Vitamin A: 99IU | Calcium: 40mg | Iron: 1mg

Nutrition Disclaimer

The provided nutrition information is generated by an automatic API and does not take variations across specific brands into account. This information is provided as a general guideline and should not be treated as official calculations. Learn more here.

Recipe created by Leslie Kiszka

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Recipe Rating


  1. These look amazing! I hear you on the wine and chocolate…that’s me too! I dont eat bread or drink milk so I dont get that concept when a storm is coming like everyone else does lol! These do look like they turned out perfect! Right up my alley, for sure!

  2. We all need ‘more fluff’ in our life LOL and these bars sure deliver that. The delicious peanut butter later and frosting, so good.

  3. These look so delicious! They certainly wouldn’t last long in my house! I’m all for nibbling the edges too!

  4. Those blondies look lovely! I am too one who gets snowed in and have to cook all day when the “lake effect” storm hits us here. Baking is a nice way to spend the day. Thanks for sharing a great recipe!

  5. Yup.. the edges are always my treat too! I’m nibbling on those because I earned it..!! Love the sounds of these bars. And I love the name too! Sounds so yum.

  6. I love, love, love, love fluffernutters! If I had my druthers growing up, I would have had them every darned day for lunch, but my mother had other plans. Your fluffernutter bars looks so incredibly delicious especially with that delightful frosting! I want and need it so I’ll be making it. And yesterday’s nor’easter really made me extra hungry with all that shoveling so I won’t feel guilty cutting off the edges and eating them.

  7. I am in love with this recipe. I love fluffer butter sandwiches. I think it’s genius to trim the uneven edges to make it smoother. I’m going to have to start doing this for all of my blondies and brownies in the future purely for aesthetic reasons. It’s not because I want to eat the edges I trim away.

  8. These looks AMAZING with all that fluff! I love how you described the texture of them. I can almost taste them. It certainly sounds like a peanut butter-lover’s dream come true.

  9. These look sooooo good! I also just love to say fluffernutter. What a fun word! I think I first heard about fluffernutters on a podcast awhile ago. Love this dessert version!

  10. I like the way you think. Why didn’t I ever consider eating the uneven edges off of my brownies, or other bars, before frosting. I mean, it’s totally for the aesthetics, right? These look amazing. I love fluffer butter, so I pinned these and plan to make them soon.

  11. Well I know for sure these would not last long in this house. They look like FUN to make…and more fun to eat. Who doesn’t love “fluffernutter”….. kids and adults go crazy for this.

  12. OK first of all I love the idea that you’ve justified trimming and eating the best part of brownies/blondies. I love the edges! And secondly – these look AMAZING! Love that you’ve used blondies as a base, and that topping looks absolutely luscious!