Peanut Butter Marshmallow Squares
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I still remember making these Peanut Butter Marshmallow Squares as a kid—three bowls, sticky fingers, and an impatient wait while the pan chilled in the fridge. They’re no-bake, ultra-simple, and hit that nostalgic sweet-salty spot. If you want a quick treat for lunchboxes, potlucks, or an easy dessert after a busy day, this recipe delivers with minimal fuss and big flavor.
Why you’ll love this dish
This recipe is exactly the kind of snack that makes life easier: no oven, few ingredients, and fast to throw together. The peanut butter gives richness and protein, marshmallows bring soft chew and volume, and graham cracker crumbs add a sandy, familiar crunch. It’s a classic for bake sales, kid-friendly parties, and those evenings when you want something indulgent without a long bake time.
“A perfect mix of gooey marshmallow and peanut butter—ready in minutes and always disappears first.” — a friend who asks me to bring these every holiday
Quick, budget-friendly, and wildly adaptable, these squares are ideal when you need a crowd-pleaser fast. If you like other peanut-butter-forward sweets, you might enjoy this peanut butter brownie squares twist too: peanut butter brownie squares.
The cooking process explained
Before you dive in, here’s a short overview so you know what to expect: melt the butter and peanut butter until smooth, whisk in powdered sugar and vanilla for sweetness and structure, then fold in mini marshmallows and graham cracker crumbs. Press the mixture into a pan, chill until firm, and slice. Total active time is about 10–15 minutes; chill time is roughly 1–2 hours depending on your fridge.
What you’ll need
- 1 cup peanut butter (smooth or crunchy; see notes)
- 1 cup marshmallows (mini work best)
- 1 cup graham cracker crumbs (about 8 full crackers crushed)
- 1/2 cup (1 stick) butter
- 1/2 cup powdered sugar
- 1 teaspoon vanilla extract
Substitutions and notes:
- Swap peanut butter for almond or sunflower seed butter for allergies.
- Use gluten-free graham-style crumbs to make the recipe gluten-free.
- If you want a less-sweet bar, reduce powdered sugar to 1/3 cup, but texture will be slightly softer. For other peanut-butter-only snacks, try these simple peanut butter oatmeal cookies: 3-ingredient peanut butter oatmeal cookies.
Step-by-step instructions
- Place the butter and peanut butter in a large microwave-safe bowl. Heat in 20–30 second bursts, stirring between each, until completely melted and smooth. (Alternatively, melt gently in a small saucepan over low heat.)
- Immediately stir in the powdered sugar and vanilla until the mixture is uniform. The powdered sugar helps firm the bars and balance the peanut butter.
- Fold in the marshmallows and graham cracker crumbs with a spatula until evenly distributed. Do this while the mixture is still warm so the crumbs absorb a bit of fat for a cohesive texture.
- Press the mixture firmly into a greased 9×9-inch pan. Use the back of a spoon or a piece of parchment to press evenly—compact bars slice cleaner.
- Refrigerate for at least 1 hour, or until set. For faster setting, place the pan uncovered in the freezer for 20–30 minutes. Cut into squares and serve chilled or at cool room temperature.
Best ways to enjoy it
These squares are terrific on their own, but here are a few serving ideas:
- Plate with fresh berries and a dusting of powdered sugar for a slightly elevated dessert.
- Serve alongside coffee, milk, or hot chocolate for a classic pairing.
- Cut smaller into bite-size pieces for party platters or candy dishes.
- Stack with a thin layer of chocolate ganache or melted chocolate drizzle for a richer treat.
How to store & freeze
- Room temperature: Not recommended for long—in warm kitchens the bars soften quickly.
- Refrigerator: Store in an airtight container for up to 4–5 days. Place parchment between layers to prevent sticking.
- Freezer: Wrap tightly in plastic wrap and place in a freezer bag. Freeze up to 2 months. Thaw overnight in the refrigerator before slicing.
Food safety note: because these are not cooked, keep them refrigerated if you’re not serving them immediately and discard if left out more than 2 hours at room temperature.
Helpful cooking tips
- Use room-temperature butter for more even melting; cold chunks can seize the peanut butter.
- Press firmly into the pan—this prevents crumbly squares. A sheet of parchment on top helps get smooth edges.
- Tiny marshmallows distribute more evenly than large ones. If using large, chop them slightly.
- For cleaner slices, chill thoroughly and use a hot knife (run under hot water and dry before slicing) between cuts.
- Want a crispier bite? Toast the graham crackers lightly before crushing.
If you’re into ultra-simple peanut butter recipes, these 3-ingredient peanut butter cookies offer a similar no-fuss approach: 3-ingredient peanut butter cookies.
Creative twists
- Chocolate swirls: Melt 2–3 ounces of chocolate and swirl it on top before chilling.
- Nutty crunch: Mix in 1/3 cup chopped roasted peanuts or pretzel bits for texture.
- S’mores version: Add a thin layer of chocolate chips on top and torch briefly for toasted marshmallow flavor.
- Vegan option: Use vegan butter, a dairy-free powdered sugar, vegan marshmallows, and a seed butter. Texture may vary slightly.
- Cookie base: Replace graham crumbs with crushed digestive biscuits or Biscoff for a spiced note.
Helpful answers
Q: How long do these take to make?
A: Active prep is about 10–15 minutes. Chilling is 1–2 hours depending on your fridge.
Q: Can I use crunchy peanut butter?
A: Yes—crunchy adds texture and works fine. Smooth gives a creamier bar.
Q: Are these kid-safe?
A: Yes—no baking or hot surfaces required if you melt in short bursts and supervise any heat. As with all sweets, cut into age-appropriate pieces.
Q: Can I bake these?
A: Baking isn’t necessary and would change the texture. These are best as a no-bake treat.
Q: Can I add protein powder or oats?
A: You can substitute up to 1/4 cup of graham crumbs with oats or protein powder, but the texture will be denser.
Conclusion
If you want more takes on the same nostalgic treat, check these classic references: the original-style Peanut Butter Marshmallow Squares Recipe, a modern blog version at Peanut Butter Marshmallow Squares – Culinary Cool, and a simple 4-ingredient spin at Peanut Butter Marshmallow Squares (4 Ingredients!) – Gluesticks Blog.
Peanut Butter Marshmallow Squares
Ingredients
Method
- Place the butter and peanut butter in a large microwave-safe bowl. Heat in 20–30 second bursts, stirring between each, until completely melted and smooth. Alternatively, melt gently in a small saucepan over low heat.
- Immediately stir in the powdered sugar and vanilla until the mixture is uniform.
- Fold in the marshmallows and graham cracker crumbs until evenly distributed while the mixture is still warm.
- Press the mixture firmly into a greased 9×9-inch pan using the back of a spoon or a piece of parchment.
- Refrigerate for at least 1 hour, or until set. For faster setting, place in the freezer for 20–30 minutes.
- Cut into squares and serve chilled or at cool room temperature.
