Mary Berry Rainbow Cake

The first time I tried this Mary Berry rainbow cake, I nearly gave up halfway through. I’d naively thought, “How hard can it be to bake a few colourful layers and slap on some frosting?” Oh, sweet summer me.

By layer three, I’d already overbaked one (dry as a biscuit), misjudged the gel food colouring on another (my “green” layer looked like a swamp), and realised too late that my fridge wasn’t big enough to chill the whole thing once assembled.

But I stuck with it—and I’m so glad I did. Because once you get the hang of the rhythm (bake, cool, repeat), the end result is absolutely worth it. This cake is a showstopper, but more than that—it tastes as good as it looks. Let me show you what I learned the hard way so yours doesn’t end up like a wobbly Leaning Tower of Rainbow.

What Makes This Recipe Special

The colours are fun, yes—but that’s not why this one stands out. What really makes it special is the base sponge. It’s light but sturdy enough to hold six layers without sagging into mush, and the cream cheese frosting has just enough tang to balance the sweetness.

Most rainbow cakes go heavy on sugar and food colouring without much thought to texture. Mary’s version? Fluffy, flavourful, and surprisingly forgiving—even when you forget to level one of the layers (guilty).

Also: using buttery spread straight from the fridge? Total game-changer. It creams beautifully without needing to wait for softening.

INGREDIENTS + WHY THEY MATTER

• Buttery spread (375g) – Surprisingly workable straight from the fridge. Gives the sponge a soft crumb without greasiness. I tried using regular butter once—it made the mix too stiff.
• Eggs (6 total) – Structure + richness. Room temperature helps them mix more evenly.
• All-purpose flour (375g) – Keeps it sturdy enough to stack. I wouldn’t recommend self-raising here—it throws off the balance with the added baking powder.
• Food colouring gels – You need gel or paste for vivid colour. Liquid food colouring makes the batter too runny, and the colours bake out dull.
• Full-fat cream cheese (275g) – Don’t use low-fat. Ever. It’ll turn your frosting runny and sad.
• Confectioners’ sugar (750g) – Sift it. Trust me. Otherwise your frosting will be lumpy and impossible to fix.

Making It Yours (Without Ruining It)

• Egg-Free? I tested with an egg replacer once (for a kid’s birthday). It just held together, but the texture was slightly gummy. I’d recommend using a tried-and-tested eggless sponge recipe and tinting that instead.
• Gluten-Free? I haven’t tested it fully GF, but you could sub a 1:1 GF blend. Be prepared for a more delicate crumb.
• Want pastel layers? Use less gel and go for a springy vibe instead of full-on rainbow.
• No cream cheese? Try a simple buttercream—just add a pinch of salt and a tablespoon of lemon juice to keep it from being too sweet.

MISTAKES I’VE MADE (AND HOW TO AVOID THEM)

What Went Wrong	Why It Happens	How to Fix It
Uneven layers	Eyeballing the batter amounts	Weigh the batter for each colour
Layers dried out	Overbaked by even 2–3 minutes	Check at 13 mins, not just 15
Frosting turned soupy	Used low-fat cream cheese	Only use full-fat, and beat it cold
Cake leaned sideways	Stacked on a slanting board	Level layers + use a spirit level

HOW TO MAKE MARY BERRY’S RAINBOW CAKE

1. Prep the tins: Preheat oven to 180°C (fan 160°C). Grease and line two 8-inch round tins.
2. Make the batter: Beat the buttery spread and sugar until pale and fluffy. Add eggs one by one. Sift in flour, baking powder, and salt. Add vanilla and milk.
3. Colour and divide: Weigh total batter. Divide evenly into six bowls. Tint each with food colouring gel—use a cocktail stick to add a bit at a time.
4. Bake in batches: Bake two layers at a time, 15 minutes each. Cool on wire racks. Re-grease and re-line tins between batches.
5. Make frosting: Beat butter and milk with half the sugar until smooth. Add rest of sugar, vanilla, and cold full-fat cream cheese. Beat just until fluffy—don’t overmix or it’ll slacken.
6. Assemble: Stack layers violet to red, spreading frosting in between. Use a thin layer for crumb coat.
7. Chill: Refrigerate for 20 minutes until frosting firms.
8. Final frost and decorate: Apply final coat of frosting. Smooth with a cake scraper. Sprinkle on nonpareils.

TIPS FROM MY KITCHEN

• I cool my cakes upside-down on the rack—helps flatten domed tops without trimming.
• My red gel always bakes duller—so I add a smidge of pink to brighten it.
• I use an offset spatula dipped in hot water to smooth the final frosting layer.
• If your frosting’s too soft, pop it in the fridge for 10 minutes—then re-whip briefly.

STORAGE + SERVING

• Room temp: Keeps 2 days in a cool spot, airtight.
• Fridge: Up to 5 days—but let it sit out before slicing.
• Freezer: Freeze the plain layers (unfrosted), wrapped in cling film and foil. Assemble fresh for best texture.
• Serving idea: It’s dreamy with a glass of cold milk or strong Earl Grey.

FREQUENTLY ASKED QUESTIONS

Q: Can I use liquid food colouring instead of gel?
A: I wouldn’t. It waters down the batter and fades during baking. Gel or paste only.

Q: My frosting keeps turning runny—what am I doing wrong?
A: Check your cream cheese. If it’s low-fat or too warm, it won’t hold. Keep it cold and full-fat.

Q: Can I bake all layers at once if I have enough tins?
A: Technically yes—but make sure your oven’s heat distribution is even. I prefer baking in batches for more control.

Q: Why does my cake lean or wobble?
A: Usually from uneven layers or soft frosting. Chill between stacking, and trim domed tops if needed.

Q: Can I make this ahead of time?
A: Absolutely. I often bake the layers a day early and wrap them well—then frost the next morning.

Try More Recipes:

• Mary Berry Gingerbread Men
• Mary Berry Doughnuts
• Mary Berry Chocolate Mirror Cake
• Mary Berry Death By Chocolate Cake