Let me just say this: marshmallow fluff is joy in a jar. There’s no other way to describe it. It’s messy and sticky and refuses to come out of the jar without a fight — but it’s also sweet, silky magic, and when you whip it with butter and vanilla, it becomes this frosting that tastes like vanilla-scented clouds.
The first time I made this icing, I didn’t even bother baking a cake. I just spread it onto digestive biscuits like a heathen and called it “research.” Mary Berry might not approve of that particular move, but I reckon she’d forgive me after one bite. This recipe is quick, nostalgic, and weirdly satisfying to make — the kind of thing that makes you feel like a kid again, licking the beaters when no one’s looking.
Why You’ll Love It
- Tastes like a soft, fluffy marshmallow but grown-up thanks to the hint of salt and real vanilla.
- Takes 10 minutes, tops — even if you get fluff stuck in your hair (it happens).
- So easy to spread or pipe — holds its shape but still melts in your mouth.
- Kid magnet — if you’re frosting cupcakes for a party, this is the one.
- Less sweet than you’d think — the butter balances it all out.
- Perfect for last-minute decorating when you forgot the buttercream or just couldn’t be bothered.
Ingredients
- 1½ sticks (170g) unsalted butter, room temperature
- 1 cup (125g) powdered sugar
- 1 tsp vanilla extract
- ½ tsp fine sea salt
- 1 jar (7 oz / ~200g) marshmallow fluff
How to Make It
Beat the butter ‘til it’s light and happy:
Pop the butter into a big mixing bowl. Beat it on high for a solid 2 minutes — it’ll go from yellow and stodgy to soft and pale. You want it almost mousse-like.
Add the sugar gently — it will try to escape:
Tip in the powdered sugar a little at a time while still beating. Don’t dump it all in or you’ll wear it. Keep going until the mix looks smooth and creamy.
Bring in the flavour:
Add the vanilla and salt. Just a touch of salt brings out the best in the marshmallow fluff. Beat again for about a minute to get everything fully blended.
Wrestle the fluff into the bowl:
Now for the fun bit. Scrape the marshmallow fluff in with a spatula — it’s sticky and stubborn, so patience is key. (A spatula sprayed lightly with oil helps heaps.)
Whip it into fluffy heaven:
Beat everything together on medium-high until it’s billowy, light, and pulling away cleanly from the sides of the bowl. If it feels too sticky, chill it for 10 minutes before spreading.
Common Mistakes and How to Dodge Them
My icing is too runny — help!
Try adding more powdered sugar, a tablespoon at a time, until it firms up. Also, check your butter wasn’t too soft or partially melted.
It’s clumpy, not smooth. What gives?
You might’ve added the sugar too fast. Next time, sift the powdered sugar and add gradually while beating.
Too sticky to work with?
Pop it in the fridge for 10–15 minutes. It’ll firm up just enough to pipe or spread without a mess.
The fluff won’t come out of the jar!
Spray your spatula or spoon with nonstick spray — makes a massive difference. Or warm the jar slightly in a bowl of warm water first.
Storage and Reheating
Fridge: Store in an airtight container for up to 1 week. Let it sit out for 10–15 minutes before using to soften.
Freezer: Freeze in a sealed tub for up to 3 months. Thaw overnight in the fridge, then give it a quick whip to bring it back to life.
Reheating: Doesn’t need it! But if it’s stiff, a quick mix with the electric beaters will revive it.
Frequently Asked Questions
Can I make this without marshmallow fluff?
Sort of. You’d need to make homemade marshmallow cream, which is faffy and involves egg whites. Honestly? Just get the fluff.
Is it good for piping?
Yes! It holds its shape nicely and looks lovely swirled onto cupcakes with a star tip.
Can I use salted butter instead?
You can — just skip the added salt or taste before adding more.
Does it crust like buttercream?
Nope, it stays soft and fluffy. Great for casual cakes, but not for fondant-covered ones.
Nutrition Facts (Per Serving):
- Calories: 410
- Fat: 24g
- Carbs: 46g
- Sugar: 30g
- Protein: 1g
- Sodium: 75mg
Try More Mary Berry Recipes:
- Mary Berry Chocolate Cupcakes
- Mary Berry Double Chocolate Chip Muffins
- Mary Berry Lemon And Coconut Cake
Mary Berry Marshmallow Icing
Description
A light and fluffy icing made with marshmallow fluff, butter, and vanilla — perfect for spreading or piping onto cupcakes, cakes, and cookies.
Ingredients
Instructions
- Beat butter until pale and fluffy, about 2 minutes.
- Gradually add powdered sugar while beating.
- Mix in vanilla and salt until combined.
- Add marshmallow fluff and beat until light and airy.
- Chill slightly if needed before using.
Notes
- Always use room temp butter for best texture.
- Sift your sugar to avoid lumps.
- Chill before piping if mixture is too soft.
- Use a greased spatula for fuss-free fluff scooping.