I first made this cake for my daughter’s birthday and everyone loved it. Especially the secret rainbow inside. It looks so fancy and I couldn’t believe how easy it was to create. I am no master baker and having previously spent days fiddling with fondant for my son’s birthday cakes, it was quite a revelation! I’d say the whole thing takes 3 hours max and most importantly, it was a lot of fun!
I shared some videos while I was making the cake on my instagram stories and had loads of messages asking for a tutorial. As I get most of my baking equipment from my local Hobbycraft this seemed like the perfect opportunity for a collaboration and I was delighted that they thought so too. Being paid to bake and craft is literally living the dream as far as I am concerned.
So who is up for making a rainbow cake?? As you can see from the photo above, mine is far from perfect but I still think it looks great. Life is too short for perfection, right? Much better to give it a go and enjoy yourself than stress about whether something is good enough. Believe me, your guests won’t be analysing it to see if you have made any mistakes, they will just be wondering how long they have to wait before they get a slice!
Below is everything you need to know in order to make your own and if you are unsure about anything, just ask. I would love to hear how you get on and see your photos.
I’ve also done an IGTV video (my first ever one – so be kind), which you can find here.
Step 1 – Make 4 x 7 inch sponge cakes
(This recipe is converted from Darina Allen’s Ballymaloe Cookery Course.)
- 250g unsalted butter at room temperature
- 350g caster sugar
- 6 medium eggs
- 350g plain flour
- 2 teaspoons baking powder
- 2 tablespoons of whole milk
Preheat your oven to 180°C/350°F/gas 4.
Line the cake tins. If you are lazy like me, I would recommend getting some 7 inch cake tin liners.
Cream the butter and gradually add the sugar. Beat until soft and pale. It will be much easier if you have an electric mixer.
Add the eggs one at a time, continuing to beat.
Sieve the flower and baking powder and stir in.
Add the milk and give a final mix to make sure everything is incorporated.
Easy as that. Just divide between the tins, hollowing slightly in the middle and cook for 20-25 minutes until a skewer comes out clean, then turn onto a wire tray to cool.
Step 2 – Make the buttercream
- 600g unsalted butter at room temperature
- 1360g white icing sugar
- 1 tspn vanilla extract
- 120ml whole milk
- 6 x gel food colours. I used Pro Gel which were fab.
(you won’t use all of this but much better to have too much than to run out)
- 7 x medium sized bowls
- 6 x piping bags. I used these disposable ones
Beat the butter for five minutes until very pale and voluminous. Again an electric mixer will really help here.
Sieve the icing sugar and add in two stages, beating for a further 3/4 minutes after each addition.
Add the vanilla extract and then slowly add the milk to loosen, until you have a good spreadable consistency. You might not need it all.
Split the buttercream between the 7 bowls. You will need more red and less of each colour of the rainbow, decreasing, so factor this in when dividing.
Leave one bowl white, to use for your crumb coat.
Add a little gel to each of the other bowls and mix well. Keep adding until you get the colour you desire. You won’t need very much.
Fill the piping bags with the coloured butter cream. There is no need for a nozzle, just snip off the end.
Step 3 – Prep the cakes
You can do this with a serrated knife but a cake leveller is really handy.
Level and trim the cakes, so that they are all flat and the same size, with smooth edges.
Step 4 – Let’s make a rainbow
You will ideally need the following:
- Cake drum
- Tall side scraper
- Small angled pallette knife
- Rainbow sprinkles
- If you will be storing or transporting the cake, you might also want a cake box.
(I would recommend that you watch the IGTV video for this part and it should all make perfect sense)
Secure the bottom layer of cake to the cake drum with some buttercream.
Pipe a circle on top of the cake with the red icing, going around the edge. The thickness of your circle should fill around 1/6 of the diameter of the cake, leaving equal room for the other colours. Next pipe an orange circle inside the red circle. Then yellow, green, blue and finally, a big purple splodge in the middle, so that the whole cake is filled.
Add another layer of cake and repeat x 2.
Add the final layer of cake and apply a crumb coat (a thin layer) of the white buttercream with your pallette knife.
Chill in the fridge for 20 minutes, while you have a cup of tea / glass of wine.
Next you need to pipe around the outside of the cake. Starting at the bottom, with purple. Each colour should go approx 1/6 up the side of the cake and the top can be covered with red buttercream, one of the reasons you will need a little extra.
It will look very messy at this stage but don’t worry as now it is time for the magic. Take your side scraper and hold it against the cake, then slowly turn the turntable to smooth out the icing.
Wipe any excess onto some greaseproof paper and keep going until you have nice smooth sides. It might take a while, so be patient. In hindsight, I should have kept going for longer with this one.
Gently tidy up the top by using your side scraper to smooth from the edges to the middle and then sprinkle with rainbow dust and wait for the applause!
Time for a celebration!! Can you believe it is that easy? If you are short on time, you could even buy pre-made cakes and simply decorate them. It would still have a great effect and no-one would know, unless you told them!
As well as a huge range of baking equipment, Hobbycraft also have a brilliant selection of rainbow themed decorations, including everything you can see here, such as this amazing balloon arch, pin wheels and party tableware.
Have a look at the website or pop into your local store for more ideas and get #hobbycrafting.