Crunchy, stretchy, chewy and made with just a few simple ingredients, this gluten-free rice bubble marshmallow slice is a crowd-pleasing treat for kids and adults alike.
Gluten free rice bubble marshmallow slice actually wasn’t on the list of recipes I’ve been working on for GFKF, but when I was working on a gluten free Rice Krispie Treat recipe for my other website, Sweetness and Bite, I realised how much they taste like LCM bars, and since LCM bars contain gluten I knew I had to share a version of this recipe here, too.
This slice gives me all of the nostalgia feels – as a kid, I often had LCM bars in my lunchbox as a treat. I hate to think that there are gluten free kiddos out there missing out on this marshmallow-y delight.
But they don’t have to, because this rice bubble slice recipe tastes so similar. Actually, I’d argue that it tastes even better, because it’s homemade. And to add even more good news, it’s super easy to make.
You only need four ingredients (plus sprinkles, if you wanna sprinkle) and it’s a no-bake slice, so you don’t even have to turn on the oven.
The recipe is basically just rice bubbles held together with a mixture of melted marshmallows and butter, which gives the rice bubble bars that chewy texture.
As you can see in the picture above, I add little mini marshmallows to the mixture, which gives you these nice little pockets of unmelted marshmallows. It’s a bit extra, but if you can’t go a little extra with such an easy recipe, then, well, when can you?
Scroll down to the recipe card for the full ingredient quantities and the printable recipe, or keep reading for a recipe overview and step-by-step photos.
Gluten free rice pops – Regular Kellogg’s rice bubbles (aka rice krispies) are not gluten free, because they contain barley malt flavouring, so make sure you choose a gluten free puffed rice cereal. I use Hubbards “Thank Goodness” gluten free rice pops, which have the crossed grain logo. If you’ve stumbled across this recipe and you don’t need the slice to be gluten free, you can use regular rice bubbles to make it.
Marshmallows – Make sure you check that your marshmallows are gluten free. My favourites for this recipe are the Ma Baker Bite Size mallows. Pascall marshmallows will work but they always have a lot of cornstarch on them, so dust off as much of that as you can so it doesn’t thicken the mixture. I also add some mini marshmallows because I like the little pockets of whole marshmallows. To make these look like LCM bars, I used only the white marshmallows, but you can use the pink ones too, your slice will just be slightly pink.
Butter – You can use salted or unsalted butter. If you use unsalted, you can add a pinch of salt to the mixture to help offset the sweetness, if you like.
Vanilla extract – I like vanilla in everything, but if you don’t have any, leave it out. There is already a bit of vanilla flavour in the marshmallows.
Sprinkles – The sprinkles are optional, but they do make an otherwise plain-looking slice more fun. Make sure you check that the sprinkles you use are gluten free, as some are not.
These are naturally egg free and nut free (just be sure to double-check each of your ingredients) and can be made dairy free by using a dairy-free spread instead of butter. Choose one that is solid, like Nuttelex. To make them vegan, you’ll also need to swap the marshmallows for gelatine-free marshmallows, like Dandies.
How to Make Rice Bubble Marshmallow Slice
I love a melt-and-mix recipe and that’s exactly what this one is.
Melt the butter in a medium saucepan over medium-low heat, then add the vanilla and toss in the marshmallows. Continue to stir over the heat until the marshmallows have all melted and the mixture is smooth. Don’t let it boil – if it starts to boil then lower the heat.
You could also do this in the microwave if you prefer, but you’ll need to heat it in short bursts, stir often, and keep a close eye on it, as marshmallows tend to puff up in the microwave.
Once the mixture is melted and smooth, you can pour it over the rice bubbles in a large bowl. Give it a good mix to ensure all of the rice bubbles are coated in the marshmallow mixture.
Add in the mini marshmallows, if using, and stir until they’re well distributed. Then press the mixture into your prepared cake tin. Make sure you just press it gently into an even layer – this will give you a nice chewy slice rather than a hard one. Sprinkle it with sprinkles, if you like (and who doesn’t?).
Once the slice has set at room temperature for 20 minutes or so, you can cut it into pieces. I cut it into long bars, but you could cut it into squares if you prefer.
Storing the Slice
The rice bubble marshmallow slice is at its most crunchy-chewy-stretchy best the day it’s made, but it will keep for 3-4 days in an airtight container.
If you’re popping it into a lunch box, make sure you keep it separate from any other items that contain a lot of moisture, as that can make the slice sticky and soft.
Fancy It Up
If you’re making this for a party, you could dress it up a bit more by drizzling the top of the slice with some melted chocolate (dark chocolate, white chocolate, milk chocolate, they’d all work here), sprinkle with chocolate chips, crumbled freeze-dried fruit, extra marshmallows.
- Only cook the marshmallow mixture long enough to melt the marshmallows and then remove it from the heat. If it gets cooked for too long then it will set hard, and the slice will be hard.
- Line your cake pan with baking paper and spray it with oil spray before you start making the slice. Once the mixture is made, it will start to cool down and set, so it needs to go into the tin straight away. It’s helpful to grease a spatula and have it ready to use to scrape the mixture out of the bowl and press it into the pan.
- To cut the slice neatly, use a large sharp knife, and give it a spray with oil before you start cutting.
- If you want to only use white marshmallows, and end up with pink marshmallows left over, I suggest making these Strawberry Rice Krispie Treats from my other website to use them up 💗.
- If you can only get jumbo marshmallows, you should cut them up a bit so they melt faster. The easiest way to do this is with kitchen scissors – lightly oil the blades first so the marshmallows don’t stick.
Looking for more gluten free lunchbox fillers?
You might want to check out my gluten free muesli bars , which can be made to suit a whole variety of dietary needs. Or for a chocolatey treat, this gluten free Weet-Bix slice might be more to your liking.
Rice Bubble Marshmallow Slice
- 175 g gluten free rice pops, (4 cups)
- 75 g butter, salted or unsalted
- 200 g marshmallows
- ½ teaspoon vanilla extract
- 30 g mini marshmallows, optional
- oil spray or melted butter, for greasing
- sprinkles, to decorate (optional)
- Grease and line an 8" square cake pan (or any roughly equivalent-sized pan) with two crisscrossed strips of baking paper. Lightly spray the baking paper with oil spray.
- Measure the rice bubbles into a very large mixing bowl, and set aside.
- In a medium-sized pot, melt the butter gently over medium-low heat.
- Add in the marshmallows and vanilla extract, and stir until the marshmallows are melted and the mixture is smooth. Don't let the mixture bubble and boil – if it starts to, lower the heat.
- Pour the melted marshmallow mixture over the rice bubbles, and mix until well combined. Stir in the mini marshmallows, if using.
- Tip the mixture into the prepared pan, and gently press it into an even layer. Don't press too firmly, or it will make the slice hard.
- Sprinkle with sprinkles, if you like.
- Leave to cool and set for 20-30 minutes at room temperature, then cut into pieces.
- Store the slice in an airtight container at room temperature for 3-4 days.