Fluffernutter bars are peanut butter bars with layers of marshmallow fluff. They are soft, chewy, and ooey, gooey treat. If you love the combination of sweet and salty, this recipe is for you!
My favourite part about this recipe is that it’s layered like a classic cookie sandwich.
The peanut butter dough comes together with just a few simple ingredients. Marshmallow fluff is added into the pan and then more cookie dough is placed on top. Then it’s baked to ooey, gooey perfection!
If you’re curious on what a fluffernutter even is, it is a simple sandwich made with peanut butter and marshmallows. The taste is perfectly sweet and nutty.
Fun fact: Fluffernutters are the reason I started putting peanut butter on my s’mores! If you haven’t tried this, you must. It’s just so good.
Why this recipe works
Easy to make – No mixer required, one bowl, and simple ingredients you can find in your pantry.
Giant cookie – It tastes like a giant cookie and is the perfect recipe to make when you don’t want to roll out a dozen individual ones.
Peanut butter bars – Soft, chewy, peanut butter dough is made for these fluffernutter bars.
Marshmallow fluff layer – Adds the perfect amount of gooeyness.
Scroll to view a few ingredients notes. Full recipe and measurements can be found in the recipe card below.
Butter – I always use unsalted butter. Remove two hours before baking.
Brown sugar – I used golden yellow, but any kind of brown sugar works.
Peanut Butter – I used creamy peanut butter in these bars, but could also use crunchy peanut butter.
Marshmallow fluff – Also known as marshmallow creme. This is an ooey-gooey marshmallow spread you can find in your baking aisle in most grocery stores. You can also make your own if you’re feeling it!
Step by step instructions
Here is how to make and bake these fluffernutter bars. You’ll need an 8×8 square pan, a whisk, a spatula, and a bowl!
Step 1 – Cream butter and peanut butter. In a large bowl, cream together butter and peanut butter until smooth. Add the brown sugar and continue to mix until smooth. Make sure there’s no brown sugar lumps!
Step 2 – Add egg and vanilla. Mix in the egg and vanilla until smooth.
Step 3 – Add in dry ingredients. Toss in the flour and salt. Fold with a spatula until no dry streaks appear.
Step 4 – Layer. Add half of the cookie dough to your prepared pan. Dollop marshmallow fluff all over and then dollop the remaining cookie dough on top of the Fluff. Smooth gently with your spatula.
Step 5 – Bake. Bake the bars for 25-32 minutes. Mine took 32 minutes exactly. The edges will be golden brown.
Expert Baking Tips
Here are a few expert baking tips from my kitchen to yours
- Do not overbake the bars! They may not look ready after 30-32 minutes, but remember that they continue to bake as they cool!
- Use room temperature ingredients. This is really important to create that smooth peanut butter dough!
- Let the bars cool for at least an hour before slicing them. The marshmallow fluff will stick to the knife if it is to warm. Speed up this process by placing it in the fridge.
- To slice smoothly: lift the bars out of the pan place on a cutting board. Slightly spray a sharp knife with non-stick cooking spray before cutting into the bars. This is optional, but it helps. You can also wipe your knife off with any extra marshmallow fluff in between each cutting to give you extra clean slices.
- I used the full sized Nutter Butter Cookies to top my bars with, but you could also use the Nutter Butter Bites if you’d like.
Why is my marshmallow fluff raised after baking?
This can happen when it’s baking, but it should go down as it cools at room temperature! If it bothers you, just lightly press it down while it’s still warm 🙂
Do I have to add Nutter Butters on top?
Can I use natural peanut butter?
No. You have to use smooth.
Storing & Freezing
Fluffernutter Bars can be stored at room temperature or in the refrigerator in an airtight container for up to three days.
I don’t recommend freezing these bars. The marshmallow fluff ends up losing it’s distinct texture.
Check out these recipes
- Hot Chocolate Cookies
- Andes Mint Brownies
- Gingerbread Espresso Blondies
- Butterscotch Oatmeal Cookies
- Preheat oven to 350°F. Line an 8×8 baking dish with parchment paper and set aside.
- In a large bowl, cream together butter and peanut butter until smooth. Add the brown sugar and continue to mix until smooth. Make sure there's no brown sugar lumps!1/2 cup butter, 1/2 cup creamy peanut butter, 3/4 cups light brown sugar
- Add in the egg and vanilla and continue mixing until smooth.1 egg, 1 tbsp vanilla
- Toss in the flour and salt and gently fold in until no dry streaks appear.1 1/2 cups all-purpose flour, 1/2 tsp salt
- In the lined and prepared pan, add half of the peanut butter dough. Then dollop tablespoons of marshmallow fluff around the dough. Take the rest of the peanut butter dough and scoop it on top. Press down evenly. Make sure it is all as even as a layer that you can get. Look at reference photos above if needed!1 cup marshmallow fluff
- Take Nutter Butter cookies and place them on top.6-8 Nutter Butter Sandwiches
- Bake the bars for 25-32 minutes. Mine took 32 minutes exactly. The edges will be golden brown.
- Allow to cool completely. If you slice while warm, the marshmallow fluff will be sticky and hard to control. I recommend waiting until it's completely cooled down, you can speed up the process by placing it in the fridge.