Bars + Brownies Desserts

Peanut Butter Marshmallow Swirl Brownies

Marshmallow Fluff + Peanut Butter + Brownies = Yes, please. And you don’t need any kind of mixer to make these – just a bowl and a whisk! They’re a combination of rich and chewy, chocolatey brownies with marshmallow fluff and a peanut butter filling swirled throughout the top.

I have a recipe for peanut butter cups in my Baking for the Holidays cookbook that I love to make, and I realized the filling would probably also taste incredible swirled into chocolate brownies. It did.

I then decided to take things one step further and twirl in some marshmallow cream!

Notes: This recipe is a variation on My Favorite Brownies recipe, and appears in my 100 Cookies cookbook. This version I actually prefer the day after they’re made, as the marshmallow fluff softens and the chocolate flavor intensifies.

More Brownie Recipes:

Marshmallow Peanut Butter Brownies

Peanut Butter Marshmallow Brownies

Servings: 24 brownies
Prep Time: 15 minutes
Cook Time: 30 minutes
Total Time: 45 minutes
The perfect brownies swirled with marshmallow fluff and peanut butter! Easy to make and are a great brownie recipe to make for parties.
Sarah Kieffer
4.34 from 6 votes
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  • Adjust an oven rack to the middle of the oven. Preheat the oven to 350F [180C]. Grease a 9 x 13 in [23 by 33 cm] baking pan (do not use glass) and line with a parchment sling.
  • In a medium bowl, mix together the peanut butter, sugar, butter, vanilla, and salt until combined and completely smooth.
  • Make the brownie batter as directed (but do not bake it!). Pour the brownie batter into the prepared pan. Dollop the peanut butter filling and the marshmallow cream over the top, alternating the two. Drag the tip of a butter knife through the batter, creating swirls.
  • Bake until the sides of the brownies have set, the top is starting to crackle and look glossy, and a wooden skewer or toothpick inserted into the center comes out with crumbs, 26 to 32 minutes. The batter on the toothpick should not be wet but should have a good amount of crumbs clinging to it. Transfer the pan to a wire rack and let cool completely. Use the parchment sling to gently lift the brownies from the pan.
  • Cut them into bars and serve. Store the brownies in an airtight container for up to 3 days.


  • Reply
    Saturday, May 6, 2023 at 12:14 pm

    1 star
    Followed the instructions step by step and used the brownie recipe referenced. Swirled everything but the top ended up burning and the batter did not bake through. Did a taste test and it tasted better as a raw batter. Not sure what happened.

  • Reply
    Thursday, January 6, 2022 at 9:33 am

    Can this recipe be cut in half? A large pan is too big for us! I couldn’t trust myself not to eat all of it!!

  • Reply
    Friday, July 30, 2021 at 5:22 am

    5 stars
    Loved by the whole family!

  • Reply
    Friday, October 30, 2020 at 8:19 am

    Really great idea. Thank you.

  • Reply
    Thursday, September 17, 2020 at 4:42 pm

    What could you use instead of peanut butter in this recipe? Thanks!

    • Reply
      Friday, April 21, 2023 at 11:55 am

      Nutella, Biscoff spread, or any nut butter

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