Peanut Butter Blondies Recipe with Marshmallows
These Peanut Butter Blondies with Marshmallows combine a peanut butter blondie base with classic Nutter Butter cookies and toasted marshmallows on top. Inspired by the peanut butter-and-marshmallow combination of a fluffernutter, they are nostalgic, delicious and easy-to-make.
These bars were gone the same day I made them. They are THAT good! From the combination of flavors to the variety of textures, each bite is absolute perfection!
A peanut butter blondie base is soft and chewy, which compliments the crunch of the nutter butter cookies and the gooeyness of the marshmallows.
These Peanut Butter Blondies are the perfect way to enjoy this magical combo of peanut butter and marshmallow. It reminds me of enjoying a fluffernutter sandwich as a kid!
Ingredient Notes and Substitutions.
- Creamy Salted Peanut Butter – A natural creamy or more processed creamy peanut butter, such as Jif or Skippy, will work in this peanut butter blondie recipe.
- Brown Sugar – Light or Dark Brown Sugar will work for this recipe. A dark brown sugar contains more molasses, resulting in a slightly fudgier blondie texture.
- Egg – Use a large-sized egg that has sat at room temperature to easily incorporate into the batter.
- Salted Butter – Make sure the butter is slightly cooled after melting it. You can also use unsalted butter, swapping at a 1:1 ratio and, if so, add a pinch of salt to balance out the sweetness.
- Vanilla Extract – Adds delicious flavor to the blondie base. You can also use vanilla pasta, swapping at a 1:1 ratio, if that is your preference or what you have available to you.
- All Purpose Flour – Measuring the flour accurately is important to ensure you have a moist, soft and chewy blondie texture. You can also make this recipe gluten-free friendly by using a gluten-free all-purpose flour, swapping at a 1:1 ratio.
- Marshmallows – Add a nice gooeyness to the peanut butter blondies and mimic the flavors of a fluffernutter. You can use any brand of marshmallows. I recommend mini-sized ones if you’re mixing them into the batter. Small or large marshmallows work for the toasting on top.
- Nutter Butter Cookies – While these aren’t a requirement for making these peanut butter blondies, they add a nice crunch and peanut butter flavor to each bite.
Topping and Mix-In Options
There are so many delicious mix-ins that you can add to this recipe. My favorites are what you see in the images: Peanut Butter, Nutter Butter Cookies and Marshmallows.
However, you can mix it up by using about a 1/2 cup of Marshmallow Fluff swirled on top instead of marshmallows. In the batter, you can mix in Peanut Butter Chips. You can put them on top of the blondie batter as well.
How to Make Peanut Butter Blondies with Marshmallows
- Preheat the oven to 350 degrees F.
- Add the egg, brown sugar, butter and vanilla extract to a bowl. Mix then add in the creamy peanut butter and mix until combined.
- Fold in the flour and mix until just combined.
- Transfer to a square 8×8 baking pan that has been lined with parchment paper or greased.
- Spread out the batter in an even layer.
- Swirl in about 2-3 tbsp of creamy peanut butter on top.
- Press 4-5 nutter butter cookies gently into the top of the blondie batter.
- Bake in the oven for 28-30 minutes, then remove the pan from the oven. Test doneness with a toothpick. If it comes out clean/with a few crumb pieces, remove from the oven. Turn the oven on Broil (High).
- Add the large marshmallow halves (or mini marshmallows) on top. Gently press into the bars.
- Put the baking tray back into the oven and broil on High for about 1-2 minutes or until the marshmallows are toasted.
- Remove from the oven and let cool completely before slicing. Enjoy!
Frequently Asked Questions
Yes! You can top the Peanut Butter Blondies with Mini Marshmallows instead of the larger ones. You won’t need to cut them in half since they are much smaller.
NOTE: They may toast more quickly, so keep an eye on them while broiling in the oven.
I prefer using a creamy, all natural peanut butter as it is looser texture than a more processed peanut butter. However, both will work in making this recipe.
TIP: Heat in the microwave at 15 second intervals to loosen up the peanut butter before adding it to the batter.
A toothpick should come out of the center clean (with maybe a few crumbs).
Yes! Let the blondies cool completely before slicing as this will allow for a clean cut.
Storage and Freezing Instructions
Store in an airtight container at room temperature for up to 3 days or in the fridge for 5 days.
You can also freeze the bars for up to 1 month in a freezer-safe container. When ready to eat, reheat in the microwave for 30-45 seconds or until warm.
Peanut Butter Blondies Recipe with Marshmallows
Ingredients
Peanut Butter Blondies
- 3/4 cup dark brown sugar
- 1/4 cup salted butter, melted
- 1/3 cup creamy salted peanut butter
- 1 large egg
- 2 tsp vanilla extract
- 1 1/4 cup all purpose flour, or all purpose gluten free flour
Toppings
- 2-3 tbsp creamy salted peanut butter, for topping
- 4-5 nutter butter cookies
- 6 large marshmallows, halved, for topping
Instructions
- Preheat the oven to 350 degrees F.
- Add the egg, brown sugar, butter and vanilla extract to a bowl.
- Mix until combined.
- Add in the creamy peanut butter and mix until combined.
- Fold in the flour and mix until just combined.
- Transfer to a square 8×8 baking pan that has been lined with parchment paper or greased.
- Spread out the batter in an even layer.
- Swirl in about 2-3 tbsp of creamy peanut butter on top and press 4-5 nutter butter cookies gently into the top of the blondie batter.
- Bake in the oven for 28-30 minutes, then remove the pan from the oven when a toothpick comes out of the center clean or with a few crumbs. Turn the oven on Broil (High).
- Add the large marshmallow halves (or mini marshmallows) on top. Gently press into the bars.
- Put back into the oven and broil on High for about 1-2 minutes or until the marshmallows are perfectly toasted.
- Remove from the oven. Let cool before slicing.
- Slice into bars and enjoy!