If you grew up loving old-school church potluck treats or those nostalgic “magic bars” your grandma used to make, these Peanut Butter Marshmallow Squares will take you right back. They’re unbelievably simple, no oven, no fuss and the flavor is pure comfort. Creamy peanut butter, sweet butterscotch, and soft marshmallows come together in one pan to create a chewy, gooey square of dessert heaven. Make a batch for parties, holidays, or just because you’re craving something sweet right now.
Step-by-Step Instructions
1. Prep your pan.
Line an 8-inch pan with parchment paper so you can lift everything out cleanly once it’s chilled.
2. Melt the base.
Warm the peanut butter, butterscotch chips, and butter together in short bursts in the microwave, stirring between each one until everything turns smooth and glossy.
3. Add the flavor.
Stir in the vanilla and a tiny pinch of salt to balance the sweetness.
4. Let it cool slightly.
Give the mixture a few minutes to cool just enough so the marshmallows don’t melt into mush.
5. Fold in the marshmallows.
Gently stir them in until every piece is coated in that peanut-butterscotch goodness.
6. Press and chill.
Spread the mixture evenly into your pan and refrigerate until firm. A couple of hours works, though overnight gives you beautifully clean slices.
7. Slice and enjoy.
Lift the slab out using the parchment, cut it into squares, and serve. They’re just as delicious cold as they are slightly softened.
💡 Notes & Tips
- Craving extra texture? Add chopped peanuts, pretzels, or crushed graham crackers.
- Prefer a different flavor? Swap the butterscotch with chocolate chips for a Reese’s-style version.
- Don’t skip the chill time, it helps the bars set without getting messy.
- Use rainbow marshmallows if you want them extra fun and colorful.
- Cut cleanly: Warm your knife under hot water, wipe it dry, then slice. Perfect edges every time.
Frequently Asked Questions
1. Why do I need to let the melted mixture cool before adding marshmallows?
If you add them too soon, they’ll melt completely instead of staying whole and pillowy.
2. Can I freeze these squares?
Yes! They freeze beautifully. Store them in an airtight container for up to a month.
3. Do they have to stay refrigerated?
They’re best kept cold so they stay firm, but they hold up well at room temperature for short periods.
4. Can I make these with crunchy peanut butter?
Absolutely! It adds great texture.
5. How long do they last?
They keep in the fridge for about five days—but they almost always disappear long before that.
Prepare an 8-inch square baking pan by spraying with cooking spray and lining with parchment paper, leaving an overhang for easy removal. Calories: Approximately 250 per square (estimated)
Protein: 4g (estimated)
Carbs: 30g (estimated)
Fat: 15g (estimated)
Ingredients
Instructions
In a microwave-safe glass bowl, melt butterscotch chips, peanut butter, and butter together in 30-second intervals, stirring in between, until smooth.
Stir in the vanilla extract and salt.
Allow the mixture to cool slightly, about 5-10 minutes, before adding the marshmallows. This prevents them from melting completely.
Gently stir in the mini marshmallows until evenly combined.
Pour the mixture into the prepared pan and spread evenly.
Refrigerate until completely set, about 2 hours, or preferably overnight for best results.
Once chilled, lift the bars out of the pan using the parchment paper overhang. Cut into squares and serve.Nutrition