These Marshmallow Peanut Butter Squares taste like something straight out of a church bake sale or Grandma’s kitchen. They’re the kind of Christmas cookie that showed up on every holiday tray and disappeared first.
The creamy peanut butter and butterscotch base wraps around soft marshmallows for that perfectly chewy, melt-in-your-mouth bite.
Tested and Verified
This recipe was tested multiple times to ensure a smooth, glossy base that coats the marshmallows evenly without melting them.
✔️ Peanut Butter Type: Use a commercial creamy peanut butter like Peter Pan, Jif, or Skippy. Natural peanut butters (the kind with oil separation) change the texture and prevent the bars from setting properly.
✔️ Butterscotch Chips: Nestlé Toll House brand melted consistently and produced the right sweetness without seizing.
✔️ Butter Ratio: The ½ cup of unsalted butter gives the base its velvety smoothness while helping the mixture firm up cleanly once chilled.
Technique Tips for a Perfect Base
Gentle Heat Only. Melt the butter, peanut butter, and butterscotch chips over medium-low heat. High heat can cause the chips to scorch or turn grainy. Stir continuously until smooth and glossy.
Cool Briefly Before Mixing. Let the mixture cool for about 2–3 minutes before pouring it over the marshmallows — this step is key. If the mixture is too hot, it’ll melt the marshmallows completely and ruin the texture.
Use a Large Mixing Bowl. Adding the marshmallows to a roomy bowl makes it easier to coat them evenly without crushing them. Fold gently to keep that pillowy bite.
Prep The Pan. Line an 8×8-inch pan with parchment paper, leaving a bit of overhang on the sides for easy lifting later. Lightly mist with non-stick spray to help the squares release cleanly once chilled.
Marshmallow Peanut Butter Squares
Ingredients
- ½ cup unsalted butter
- 1 cup creamy peanut butter, Peter Pan brand used
- 11 ounces butterscotch chips, Nestle Toll House brand used
- 1 teaspoon vanilla extract
- 10 ounces 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 to 4 quart saucepan, over medium-low heat, add the unsalted butter, creamy peanut butter, and butterscotch chips. Stir until melted and smooth.
- Stir in the vanilla extract and remove from the heat and allow the mixture to cool for 2 to 3 minutes to ensure the marshmallows don’t melt when mixed in.
- 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.
- Transfer the mixture to the prepared pan and spread into an even layer.
- Chill for 1 ½ to 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.
Notes
Be sure to use a standard commercial creamy peanut butter (JIF, Peter Pan or Skippy brands) for this recipe. The natural or flavored varieties will not yield the same texture or taste.
Nutrition
Serving and Storing
These peanut butter marshmallow squares are perfect for bake sales, potlucks, and Christmas cookie trays.
When it’s time to slice, warm your knife under hot water, dry it, and wipe between cuts for clean, smooth edges. Cutting the bars into 16 squares (about 2×2 inches each) gives the perfect balance — rich enough to feel indulgent without being overwhelming.
For best texture and freshness, store the squares covered in the refrigerator. The chilled temperature keeps the peanut butter–butterscotch base firm and prevents the marshmallows from getting sticky.
- Refrigerator: Store in an airtight container for up to one week. Let them sit at room temperature for about 10 minutes before serving for the perfect chewy bite.
- Freezer: Freeze whole or sliced squares in a single layer, then transfer to a freezer-safe container or bag once solid. They’ll keep well for up to two months. Thaw overnight in the fridge before serving.
- Room temperature: Safe for short periods (like a few hours at a party), but prolonged warmth will make them soft and greasy.
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Comments
Doris says
Recipe sounds delicious – am anxious to try it. Am wondering if I can melt the chips, peanut butter, etc in the microwave. Thanks
Layne Kangas says
Hi, Doris – we haven’t tested it in the microwave so I’m not sure how that would turn out. I would be worried they might overheat and impact the final product, as heating up in the microwave can be inconsistent sometimes as opposed to stove top. Please let me know if you try them!
Frank says
It could work but you will need to do it in short bursts and mix well between each one.
Marilyn Gallagher says
Hi, these look very tasty and would no doubt be liked by everyone from kids to adults. But because I have had thyroid cancer as well as being allergic to soy, could I substitute the butterscotch chips for an allergy-free chocolate chip such as the Enjoy Life brand? I wish they would make the butterscotch flavor with no soy.
Layne Kangas says
Hi, Marilyn – we haven’t tried that but I think it would be yummy! Enjoy!
Laura says
Our family is obsessed with this delicious treat!