Name: Peanut Butter Marshmallow Squares
Prep time: 5 min
Total time: 95 min
Ingredients: ½ cup unsalted butter; 1 cup creamy peanut butter (Peter Pan brand used); 11 ounce bag butterscotch chips (Nestle Toll House brand used); 1 teaspoon vanilla extract; 10 ounce bag fruity-flavored mini marshmallows (Jet-Puffed brand used)

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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.

A stack of peanut butter marshmallow squares topped with colorful cereal bits sits next to a bowl of peanut butter and a glass of milk.

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

Peanut Butter Marshmallow Squares ingredients.

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.

Recipe Variations

Chocolate Peanut Butter Marshmallow Squares – Drizzle melted chocolate or stir in chocolate chips for a rich, chocolatey twist.
Holiday colors – Use red and green marshmallows for Christmas or pastel ones for Easter for a festive touch.
Crunchy version – Mix in chopped peanuts, Cheerios, or shredded coconut before chilling for extra texture.
Marshmallow Peanut Butter Rice Krispie Squares – Fold in 1 cup of Rice Krispies cereal for a fun crunch, just like my Peanut Butter Rice Krispie Treats.
Nut-free swap – Substitute sunflower seed butter for a similar creamy texture and flavor without peanuts.
Extra sweet – Spread a layer of melted butterscotch chips on top before chilling for a fudge-like finish.

Golden peanut butter marshmallow squares cut into pieces on a wooden board, next to glasses of milk and a bowl of colorful marshmallows.

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 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.
Chill the bars: Spread the mixture evenly into the prepared pan. Refrigerate for 1½ to 2 hours, or until completely firm.
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.

Recipe Tips

Prep first: Line a square pan and have the marshmallows ready before melting the peanut butter mixture—this recipe comes together fast.
Use gentle heat: Melt the butter, peanut butter, and butterscotch chips over medium-low heat to prevent scorching or separating.
Cool slightly: Let the peanut butter mixture rest for a couple of minutes before adding the marshmallows so they stay soft and whole.
Don’t overmix: Gently fold until the marshmallows are evenly coated; overmixing can cause them to melt or lose their shape.
Clean slices: Run a sharp knife under hot water and wipe between cuts for smooth, bakery-style squares.
Storage shortcut: Stack slices with parchment paper between layers in an airtight container to keep them from sticking.

A close-up of a peanut butter marshmallow square with a bite missing, showing colorful marshmallows and cereal bits.

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.

Stack of colorful peanut butter marshmallow squares on a white plate next to a glass of milk.

More Easy Dessert Recipes

Love no bake treats? Try these simple, sweet recipes that disappear as quickly as these Peanut Butter and Marshmallow Squares!

Butterscotch Fudge – Rich, creamy, and made with just a few pantry staples.
Peanut Butter Fudge – Smooth, melt-in-your-mouth fudge that’s full of classic peanut butter flavor.
Monster Cookie Energy Balls – No bake bites packed with oats, peanut butter, and mini M&Ms for a fun, chewy snack.
Rocky Road Fudge – Loaded with marshmallows and chocolate for a soft, crunchy, irresistible treat.

If you’ve tried this Peanut Butter Marshmallow Squares Recipe or any other recipe on my website, please leave a star rating and let me know how it turned out in the comments below.

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Peanut Butter Marshmallow Squares

Author — Jennifer Fishkind

Serves —

Soft, chewy, no bake peanut butter marshmallow squares made with just five simple ingredients. Sweet, buttery, and ready in minutes for quick, nostalgic no bake treats.

Print Rate Pin Save

Prep Time 5

Chill time 1 30

Total Time 1 35

Ingredients

▢ ½ cup unsalted butter
▢ 1 cup creamy peanut butter Peter Pan brand used
▢ 11 ounce bag butterscotch chips Nestle Toll House brand used
▢ 1 teaspoon vanilla extract
▢ 10 ounce bag fruity-flavored mini marshmallows Jet-Puffed brand used

Instructions

Line a 8×8 straight-sided baking pan with parchment paper, leaving enough to overhang the sides, then lightly spray with non-stick baker’s spray. This helps to remove the chilled squares from the pan when ready to slice.
In a 3 ½ – 4 quart saucepan, over medium-low heat, add the unsalted butter, creamy peanut butter, and butterscotch chips. Stir until melted and smooth.
½ cup unsalted butter, 1 cup creamy peanut butter, 11 ounce bag butterscotch chips
Stir in the vanilla extract and remove from the heat and allow the mixture to cool for 2-3 minutes to ensure the marshmallows don’t melt when mixed in.
1 teaspoon vanilla extract
Add the mini marshmallows to a large mixing bowl, pour the slightly cooled peanut butter mixture over the marshmallows and gently fold to combine until all the mini-marshmallows are evenly coated.
10 ounce bag fruity-flavored mini marshmallows
Transfer the mixture to the prepared pan and spread into an even layer.
Chill for 1 ½ – 2 hours or until completely firm.
Gently lift the peanut butter bars from the pan using the overhanging parchment paper and place onto a large cutting board.
Slice into 16 squares using a large sharp knife. You can run the knife under hot water and wipe clean between slices for smooth cuts.

Jenn’s Notes

Storage :

Store: Keep in an airtight container in the refrigerator for up to 1 week.
Reheat: Best enjoyed chilled or at room temperature. Avoid microwaving, as the marshmallows may melt.
Freeze: Wrap uncut bars tightly in waxed paper and plastic wrap, then freeze for up to 3 months. Thaw overnight in the refrigerator before slicing.
Make ahead: Ideal for holidays or parties. Prepare up to 2 days ahead and keep chilled until serving.

Tips:

Prep first: Have your pan lined and marshmallows ready before you melt the peanut butter mixture. Once melted, everything comes together quickly.
Use gentle heat: Melt over medium-low heat to prevent scorching or separation.
Cool slightly: Let the peanut butter mixture rest a couple of minutes before mixing with marshmallows so they don’t turn into a sticky puddle.
Don’t overmix: Gently fold the mixture until marshmallows are coated.
Overmixing can cause them to break down.
Clean slices: Run your knife under hot water and wipe between cuts for smooth, bakery-style squares.
Storage shortcut: Stack slices with parchment paper between layers to keep them from sticking together.