Now Reading
Marshmallow Peanut Butter Cookie Bars

Marshmallow Peanut Butter Cookie Bars

These marshmallow peanut butter cookie bars are filled with peanut butter cups, chocolate chips, and marshmallow fluff. Ridiculously rich and totally delicious.

I made you something that’s kind of, well, not to be too obnoxious about the whole thing… AMAZING.

Well, it’s only amazing if you’re a peanut butter and chocolate kind of person, which, unless there’s an allergy or some weird dietary restrictions, should probably be everyone.

While I might be a bit biased about the whole thing (because clearly I adore chocolate and peanut butter—cue this Chocolate Chip Cookie Peanut Butter Cream Pie, and these Gooey Peanut Butter Crumb Bars), I got some pretty rave reviews over these bad boys.

(Legit reviews, guys, I promise. Not just me telling myself how great they are. ?)

These Marshmallow Peanut Butter Chocolate Chip Cookie Bars combine everything I love about chocolate and peanut butter into one intensely rich, ridiculously gooey, over-the-top dessert bar.

Not to talk these peanut butter chocolate chip cookie bars up too much, similarly to these Strawberry Blondies, this was one of those recipes where I was shocked at how good these were.

I expected these to be pretty good (because Reeses peanut butter cups), but these were shockingly incredible.

See Also
Peanut Butter and Banana Cake

Marshmallow Peanut Butter Chocolate Chip Cookie Bars Tips & Tricks:
-The base of these bars is a peanut butter chocolate chip cookie recipe. Peanut butter is substituted for half of the butter in my favorite chocolate chip cookie recipe, and Reeses peanut butter cups are also substituted for half of the chocolate chips.

-You need to use marshmallow fluff, not marshmallows. The marshmallow fluff is what gives these bars that gooey marshmallow filling, and it stays soft and gooey even after baked. Regular marshmallows are a bit more temperamental when baked, and often times they can disintegrate at high temperatures and/or become hard and chewy.

-These bars are very thick, thus you do want to bake these bars until the top is lightly golden brown. The center of the bars will be soft and gooey and perfect.

clock clock iconcutlery cutlery iconflag flag iconfolder folder iconinstagram instagram iconpinterest pinterest iconfacebook facebook iconprint print iconsquares squares iconheart heart iconheart solid heart solid icon

Marshmallow Peanut Butter Cookie Bars

5 Stars 4 Stars 3 Stars 2 Stars 1 Star

No reviews

  • Author: Michelle Verkade
  • Total Time: 50 minutes
  • Yield: 12 bars 1x


  • 1/2 cup peanut butter (room temperature (I used all-natural))
  • 1/2 cup butter (softened to room temperature)
  • 1 cup brown sugar
  • 3/4 cup granulated sugar
  • 2 eggs
  • 2 1/2 tsp vanilla extract
  • 1 tsp baking soda
  • 1 tsp salt
  • 2 1/2 cups all purpose flour
  • 1 cup Reeses peanut butter cups (chopped into small pieces)
  • 1 cup semi-sweet chocolate chips
  • 1 7 oz jar marshmallow fluff


  1. Preheat oven to 350 degrees and line a 9×9 or 11×7 baking dish with non-stick foil or grease with baking spray (9×9 will yield thicker bars while 11×7 will be slightly thinner). Set aside.
  2. In a bowl, mix butter and peanut butter together until combined.
  3. Add in brown sugar and granulated sugar, and mix until combined.
  4. Add in eggs, one at a time, stirring well after each addition.
  5. Mix in vanilla extract.
  6. Add in baking soda, salt, and all-purpose flour, and mix until combined.
  7. Lastly, add in Reeses peanut butter cups (chopped into small pieces) and chocolate chips, mixing until combined (dough will be thick).
  8. Spread half of the dough evenly over the bottom of the pan. Set aside the rest of the dough.
  9. Spread the marshmallow fluff on top of the dough (the marshmallow fluff is sticky, but spread it out as best you can).
  10. Press/spread the remaining dough on top of the marshmallow fluff in an even layer(it’s okay if some of the marshmallow fluff is showing).
  11. Bake for about 25 minutes, or until the top is lightly golden brown.
  12. Allow the bars to cool for at least 30 minutes (I prefer to cool for at least an hour) before cutting into them.
  13. Enjoy!
  14. Store remaining bars in an airtight container (they’re fine at room temperature, if it’s not too hot, for up to 4-5 days).
  • Prep Time: 25 minutes
  • Cook Time: 25 minutes
  • Category: Baking


View Comments (0)

Leave a Reply

Your email address will not be published.

Recipe rating 5 Stars 4 Stars 3 Stars 2 Stars 1 Star

Scroll To Top