These Peanut Butter Marshmallow Squares take me straight back to the dessert trays I used to raid at every family gathering. They’re sweet, chewy, and loaded with peanut butter and butterscotch flavor. I love how easy they come together (just 5 minutes on the stove!) and how the colorful marshmallows make each bit a little pop of nostalgia.
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Why I Love This Recipe
There’s something so fun and nostalgic about these Peanut Butter Marshmallow bars, they remind me of the colorful, chewy treats my grandman used to make and still can’t resist today.
- Only 5 simple ingredients, no baking needed
- Soft, chewy, and peanut buttery flavor with a hint of butterscotch
- Quick to make and great for potlucks, after-school snacks, bake sales, or gifting
- A fun dessert to make (or share) with the kids that stores and travels well
- Easy to customize with melted chocolate, cereal, or colorful marshmallows for any occasion
Love marshmallow desserts? You’ll also enjoy my Marshmallow Fudge and chewy Rocky Road Bars, both made with simple pantry staples.
Ingredients Notes
- Unsalted butter – Adds richness and helps everything melt together smoothly. Salted butter works fine too; just skip any added salt in the recipe.
- Creamy peanut butter – Use a standard smooth peanut butter like JIF, Peter Pan, or Skippy for the best texture and flavor. Avoid natural peanut butter or flavored varieties since they can cause the bars to separate. Crunchy peanut butter works if you want a little extra texture.
- Butterscotch chips (Nestlé Toll House brand used) – Sweet and buttery! You can also swap in peanut butter chips for a fun twist.
- Pure vanilla extract – Adds warmth and depth. Almond extract also tastes great for a light nutty note.
- Fruity-flavored mini marshmallows (Jet-Puffed brand used) – Bring color, chewiness, and a hint of fruit flavor. You can substitute plain white mini marshmallows if you prefer a classic version.
See the recipe card for full information on ingredients and quantities.
How to Make Peanut Butter Marshmallow Squares
- Prepare the pan: Line a 8 inch pan with parchment paper, leaving a bit of overhang for easy removal, and lightly spray with nonstick baker’s spray.
- Melt the mixture: In a medium saucepan over medium-low heat, combine the butter, peanut butter, and butterscotch chips. Stir until smooth and melted, then mix in the vanilla. Remove from heat and let cool for 2 to 3 minutes so the marshmallows don’t melt.
![mix ingredients in the pan.]()
- Mix in marshmallows: Add the mini marshmallows to a large mixing bowl. Pour the warm peanut butter mixture over top and gently fold until all the marshmallows are evenly coated.
![mix in the marshmallows in a bowl.]()
- Chill the bars: Spread the mixture evenly into the prepared pan. Refrigerate for 1½ to 2 hours, or until completely firm.
![pour into the pan and chill.]()
- Slice and serve: Lift the chilled bars out using the parchment paper and place on a cutting board. Slice into squares with a sharp knife, wiping the blade clean between cuts for smooth edges.
My marshmallows melted, what happened?
The peanut butter mixture was likely too hot when you added it to the marshmallows. Let it cool for about 2–3 minutes before mixing, just enough so it’s still warm and pourable, but not hot enough to melt the marshmallows.
Make Ahead & Storage Instructions
- Store: Keep the squares in an airtight container in the refrigerator for up to 1 week.
- Reheat: Best enjoyed chilled or at room temperature; avoid using the microwave, as the marshmallows may melt.
- Freeze: Wrap uncut bars tightly in a single layer in waxed paper and plastic wrap, then store in the freezer for up to 3 months. Thaw overnight in the fridge before slicing.
- Make ahead: Perfect for holidays or parties. Prepare up to 2 days in advance and keep refrigerated until serving.
