A few of my mummy friends commented on how much they loved Cai’s Rainbow birthday cake and would like to do the same for their babies birthdays, so I wanted to share the recipe and my tips for making it.
First big tip is to buy the gel colours not liquid colouring, you won’t get the bright colours with liquid colourings more of a pastel effect.
Second tip is when baking the cakes open the oven from time to time to make the cake flat. Normally we wouldn’t want this but as this is a layer cake and we want the layers to be as level as possible to get that seamless effect.
I used 2 cake tins and cooked 2 layers at a time. Found this worked well with giving enough time for cooling. Also allowed time for colouring of the mixture for next two layers whilst the other layers were baking.
150g butter softened // 300g Philadelphia (must be full fat) // 900g Icing sugar // 3 teaspoons of vanilla extract
Preheat oven to 180C / 160 fan / gas 5
Cream together butter and sugar until light and fluffy (3-4 minutes) using an electric whisk
Add egg a little at a time to avoid curdling
Add flour bit by bit to stop the egg splitting
Add vanilla extract
Mix well but don’t over mix
Grease and line 2 cake tins. Divide mixture into 6 portions, weigh to ensure equal weights. Add Wilton colour gels to each bowl, a little bit at a time as colours are strong. Use a cocktail stick to prevent dying your hands
Put 2 tins at a time in the oven for 16-18 minutes. Put a piece of greaseproof paper over the top to prevent browning. Test with a cocktail stick in the middle to check cooked well. Set aside to cool and reuse tins for the next 4 colours
Once all layers are cooked and cooled you are ready to put them together to make your cake. Place purple layer on your cake stand ready for buttercream. Use a whisk to mix all of the above buttercream ingredients together. Use very thin layer of buttercream between layers. Put weights on top to compress layers together for about 30mins. This helps give the effect that its one whole cake
Once your layers are all buttercreamed together you are ready to cover the cake in buttercream. Best to cover with a thin layer of buttercream first, known as a crumb coating and then refrigerate for 30mins
Once refrigerated the buttercream goes harder and is a good base for a thicker coating of buttercream. Use a spatula for a smoother finish
Now your ready to decorate. I used mini Smarties around the base and edged with rainbow coloured sprinkles. I made a cardboard number one that I glued the same sprinkles too, this gave the effect of the 1 being made of cake too :)
That’s it top with candles or sparkles and get ready to wow people when you cut it open!