[Updated 21/11/2023] If you are on the hunt for the easy, quick and beginner-friendly rainbow layer cake recipe you can ever find, you've just found it.
Why is the Anges de Sucre rainbow cake recipe the easiest and quickest ever? Here are three solid reasons why:
1. This rainbow cake sponge layer recipe is simple and foolproof. You can even buy our secret recipe.
2. The secret, yet very commonplace ingredient, in this rainbow cake recipe gives it a beautiful flavour and keeps the layers incredibly moist for days.
3. Minimal effort to decorate a truly gorgeous rainbow cake, but complex enough to make anyone feel like a super baker (basically a beginner baker can muddle through).
Ooooh, "secret ingredient"...what's that?! I haven't just plugged that as click-bait, neither am I intentionally trying to lure you with a big reveal...but it's an ingredient that most households have in their fridge as a staple and most cake recipes overlook.
When people think of delicious home-baked cake ingredients they think butter, eggs, flour, sugar. For the most part, these are all great for a good bake but I prefer to omit butter from my sponge recipes as our buttercream recipe contains a lot of whipped butter anyway. Instead we use vegetable oil as I feel it helps keep a cake moist for longer.
You're thinking, "Hang on Reshmi, oil in cake recipes is hardly an earth-shattering secret...?! LOADS of cake sponge recipes are oil-based!". Yup, loads are. But the OTHER ingredient, that not only helps add moisture to the sponge and a gorgeous almost-twangy flavour lifting it up from being a basic vanilla sponge, is indeed often ignored, not sung about, yet found everywhere.
Plain ol' yoghurt has transformed my basic vanilla sponge recipe and I am surprised more recipes don't call for it. Buttermilk is another ingredient that is delightful and can be substituted straight for yoghurt but it isn't as readily available. If however you find yourself in the midst of the apocalypse and there is not a scrap of yoghurt or buttermilk in the shops, you can make your own with whole milk and lemon juice or vinegar - for every cup of milk, stir in 1 tablespoon of lemon juice/vinegar and let curdle for 5 minutes et voila (although if it really is the apocalypse, perhaps making a rainbow cake isn't high up on your agenda).
The crumb texture of the sponges made with yoghurt is so light and tender. It's also moist yet without a hint of greasy mouth-feel that can happen with an oil-based cake recipe. And having shunned rainbow cakes for as long as I have, I thought there needs to be something else that appeals other than simply the way it looks with the layers of rainbow dyed sponges...and here it is - a delicious, vanilla-ey, soft and tender, with the slightest touch of tangyness, and beautifully pastel coloured layered rainbow cake! Literally, the QUEEN of rainbow cake recipes, this one is!
Rainbow Layer Cake Recipe
For 5x 6" sponge layers
380g caster sugar
120ml oil (any neutral oil, eg: vegetable or sunflower)
3 eggs (medium, or a mix)
1 tablespoon vanilla extract
120g yoghurt (full, low, or fat-free)
350g all-purpose plain flour, sifted
3 teaspoon baking powder
1 teaspoon salt
300ml milk (whole or semi-skimmed)
Food colours (I prefer gel pastes in pink, green, yellow, blue and purple)
1. Pre-heat oven to 170 degrees Celsius and prepare five of the 6" round cake tins by greasing well with oil or butter and sprinkling an even layer of flour over.
2. In a large mixing bowl, beat together the eggs, oil and sugar until light.
3. Stir in the yoghurt (or buttermilk) slowly to combine.
4. Add in the dry ingredients, milk and vanilla gradually and beat until just combined. Divide the batter evenly into 5 bowls.
5. Using pinch amounts of food colouring, mix in each colour into the bowls to create pastel pink, yellow, green, blue and purple cake batter. For brighter layers you can mix in an eighth of a teaspoon of food colour in each but in my opinion the pastel or mid-tone colours are far more appetising. Pour the coloured batters into the prepared cake tins and bake for 20-25 minutes or until a wooden skewer comes out clean.
6. Once baked, pull the tins out of the oven and let rest for 10 minutes before releasing the sponges from the tins and letting cool completely on a wire rack.
150g egg white at room temperature
225g granulated sugar
300g butter at room temperature
1 tsp vanilla extract
Pinch of salt
Optional Food colours (I prefer gel pastes in pink, green, yellow, blue and purple)
1. Follow my smooth Swiss meringue buttercream recipe for a smooth and silky frosting finish, or use any other that you prefer (but it needs to be of piping and covering consistency).
2. If you'd like coloured buttercreams, spoon 3 tablespoons of buttercream into five different bowls and using pinch amounts of food colour mix buttercream into pastel shades of pink, green, yellow, blue and purple.
Decorating Rainbow Layer Cake
Any other decorating items such as meringues, macarons, rainbow chocolate shards, rainbow sweets etc
1. Smear a dollop of icing in the centre of an 8" cake board using a cranked palette knife. Place the purple sponge layer in the middle and smooth a layer of vanilla buttercream over it.
2. Sandwich and build up the sponge layers with buttercream followed by the blue, green, yellow and pink sponges.
3. Crumb coat the outer edges of the cake with vanilla buttercream and smooth using the edge of the palette knife or a cake scraper. Chill in the fridge to set for 10-15 minutes.
4. Smooth another layer of vanilla buttercream all over and smooth using the edge of the palette knife or cake scraper. Using a decorating turn-table helps massively to make getting that smooth finish a lot easier.
5. Your delightfully delicious rainbow cake is now ready as it is or you can further jazz it up with sprinkles and piping coloured buttercream swirls over the top using star or savoy piping nozzles fitted in piping bags, and placing meringue kisses, macarons, and rainbow sweets - it doesn't really matter because once that cake is cut the layers do all the talking, singing and dancing.
I feel like I've missed out my whole life having dismissed and under-estimated the amazingness of rainbow cake, writing it off as just "sponge with colour". I've had two slices of this cake in one sitting and am perplexed, and ever-so-slightly worried about not feeling grossly caked-out...that's how more-ish it is.
This rainbow cake is more of a faff than straight up vanilla, but cutting it is SO EXCITING, and as I mentioned earlier, the yoghurt makes it all taste INCREDIBLE. If you make this, please do share on Instagram and tag me @angesdesucre #angesdesucre so I can feast with my eyes too and crash your cyber-cake party!
If you have any rainbow-cake related thoughts or questions, pop them down below in the comments. Happy rainbow-cake-baking!
Lots of love,