Desserts
Classic Marshmallow Rice Krispies Squares
Why This Recipe Works
- Melting the butter and marshmallows over low heat keeps the mixture smooth instead of cooking it until it becomes stiff or overly sticky.
- The cereal is folded in only after the pan comes off the heat, so it becomes evenly coated without being crushed or softened unnecessarily.
- Pressing the mixture into the tin gently rather than compacting it firmly helps the finished squares stay light and chewy instead of dense.
- A small amount of vanilla and optional salt balance the sweetness without changing the familiar marshmallow-and-cereal flavour.
Pro Tip
Press the mixture into the tin only lightly; packing it firmly can make the squares dense. Fold reserved marshmallows in while the mixture is still warm for softer pockets throughout.
Serving Suggestion
Let the slab set completely before lifting it from the tin and cutting it into squares. A sharp knife gives cleaner edges, and wiping the blade between cuts can help if the marshmallow mixture is sticky. Serve the squares at room temperature, where the cereal stays crisp and the marshmallow layer remains soft and chewy.
Key Ingredient: 300g mini marshmallows
Mini marshmallows melt quickly and evenly. Reserve some to fold in at the end if you want softer marshmallow pockets through the squares.
Introduction
Four ingredients and no oven: butter and marshmallows melt together on the hob, the cereal folds in off the heat, and the only wait is for the slab to set at room temperature. The main risk to a soft, chewy square isn't the method — it's using marshmallows that have gone slightly stale, since dried-out marshmallows don't melt properly and leave the finished bars dense rather than gooey.
Allow about 10 minutes to prepare, plus 30 minutes to set. It makes 16 squares.
What You'll Need
Ingredients
- 55g unsalted butter
- 300g mini marshmallows
- 150g crisped rice cereal
- ½ tsp vanilla extract
- Fine salt, to taste (optional)
Use marshmallows that are soft and fresh, not ones that have dried out in an open bag — stale marshmallows resist melting and leave gritty lumps rather than a smooth, stretchy mixture.
How to Make Classic Marshmallow Rice Krispies Squares
Melt the Butter and Marshmallows
- Line a 23 × 33cm baking tin with baking parchment, leaving some overhang at the sides. Melt the butter in a large saucepan over low heat. Add the mini marshmallows, reserving about 1 cup to fold in later, and stir constantly over low heat until completely melted and smooth.
Fold in the Cereal
- Remove the pan from the heat and stir in the vanilla extract and optional salt. Gently fold in the cereal until evenly coated, then fold in the reserved marshmallows.
Chill or Set
- Transfer the mixture to the prepared tin. Using a lightly greased spatula or a piece of baking parchment, press it into an even layer, pressing only lightly to level the surface rather than packing it down firmly — a firmly packed mixture squeezes out the air pockets and makes the squares dense. Leave to set at room temperature for about 30 minutes, then lift out using the parchment and cut into 16 squares.
Tips for the Best Results
- Use fresh marshmallows
- Stale ones don't melt smoothly and are the single biggest cause of hard, gritty squares.
- Keep the heat low throughout
- High heat cooks the marshmallow mixture further than it needs to go, which sets harder once cooled.
- Press gently, not firmly
- Light pressure levels the surface while keeping the air pockets that make the squares soft and chewy.
- Fold in reserved marshmallows while the mixture is still warm
- This leaves soft, slightly under-melted pockets through the finished squares.
How to Store and Freeze Classic Marshmallow Rice Krispies Squares
Store in an airtight container at room temperature for up to 3 days, with baking parchment between layers if stacking them. Don't refrigerate them — the cold firms the marshmallow and makes the squares noticeably harder, not softer. For longer storage, wrap individual squares tightly and freeze for up to 6 weeks; thaw at room temperature before eating.
Substitutions and Variations
- Chocolate drizzle
- melt 50g milk, dark or white chocolate and drizzle it over the cooled, cut squares.
- Peanut butter
- stir 1 tbsp smooth peanut butter into the melted marshmallow mixture before adding the cereal.
- Large marshmallows
- use the same total weight of large marshmallows instead of mini, cut into smaller pieces first so they melt evenly.
- Nutty crunch
- fold in 50g toasted pecans, peanuts or almonds along with the cereal.
Frequently Asked Questions
- Can I use large marshmallows?
- Yes. Measure them by the same total weight as the mini marshmallows and cut them into smaller pieces first so they melt more evenly.
- Can I refrigerate these to make them set faster?
- It isn't recommended — the fridge firms the marshmallow and makes the squares harder rather than helping. Let them set at room temperature instead.
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