Gluten Free Rainbow Cake

I’ve had a fair amount of success adapting the Sweetapolita recipes to gluten free, so thought I would give the ever-popular, all-over-the-web, 6 layered rainbow cake a go.  I wanted a cake that would fit nicely with our free rainbow printables, and one that I could consume myself post photos!  Lucky for me, it turned out nicely, and the leftovers were much appreciated by my workmates the next day (I couldn’t possibly risk myself or my own kids consuming all that sugar and food colouring by ourselves!).

Here’s the recipe – the gluten free, free range egg version (note, the original recipe that Sweetapolita used was from Whisk Kid).

Ingredients
225g butter at room temperature (get it out of the fridge a good couple of hours beforehand)
2 1/3 cup sugar
¾ cup egg whites (approx. 6 free range eggs)
2 tsp natural vanilla extract
3 cups Healtheries gluten free baking mix (or other gluten free baking mix or cake flour)
4 tsp gluten free baking powder
½ tsp salt
1 ½ cup milk
Gel food colourings (red, orange, yellow, green, blue and purple – you can mix red & yellow to get orange, and blue and yellow to get green if need be)

Method
Preheat the oven to 180°C.  Spray 6 (or however many you have) 25cm cake pans with rice brain oil spray, or grease lightly with butter.  Line the bottoms with a circle of baking paper (use the base of the cake pan to trace a circle on the baking paper and cut out to get the perfect circle).

Put the baking mix, baking powder and salt in a bowl and whisk to mix thoroughly.

In the bowl of an electric cake mixer, cream the butter and sugar.  Then add the egg whites a little at a time.  Add the vanilla and mix. 

Warm the milk in the microwave for 30 seconds.

Then, alternating between the dry ingredients, and the milk, add in two parts.  Stop and scrape down the sides and bottom of your bowl, and mix until fully incorporated.

Divide the batter evenly into 6 bowls and then whisk food colouring into each bowl (I used a ¼ tsp measure of each colour) – the colour of the batter needs to be the desired colour of your cake.
Pour the batter into the cake pans and bake for 15 minutes each (I baked two at a time).

Once baked, let them cool in the cake pan for 10-15 minutes, and then turn them onto a rack to cool.

Swiss Meringue Buttercream
You’ll need to make the buttercream in two lots – it’s far too much for a single bowl.  The method for each is the same, just the quantities required differ.

Filling:
10 free range egg whites
1 ¾ cup sugar
400g butter
2 tsp natural vanilla extract

Frosting:
6 free range egg whites
1 cup sugar
225g butter
1 tsp natural vanilla extract

In a saucepan, cook the egg whites and sugar, until the sugar is completely dissolved (use a medium heat and whisk constantly.  You know the sugar is dissolved when you rub the egg white between your fingers and it doesn’t feel at all gritty).

Using an electric cake mixer on high, beat the egg white and sugar mix until soft peaks form (just like pavlova mixture).  Keep the mixer going and add a little bit of butter at a time (I did it in roughly 25g lots).

Add the vanilla and whip for 5-10 minutes until it has the consistency you would expect of a buttercream.  If for some reason it doesn’t come together, put it into the fridge for 10 minutes, and then take it out and mix again.

To Assemble
Basically, just stack and layer as you would expect – the purple layer goes on the bottom, add a layer of buttercream, then the blue layer, another layer of buttercream and so on.  Note, the buttercream layers are about as thick as the cake layers!

For the frosting, use a long, straight end spatula to get the frosting smooth.  If you want it a bit closer to perfect than I did it, dip a long straight knife in hot water and use that to spread it.

And if you want absolutely perfect and flat, you could do a final layer of white fondant.