Rainbow cake

⇐ Bread & Baking

This was my invention using standard patisserie recipes. As each sponge layer needs to coloured separately, you can't make a large sponge and cut out several circles or squares. So I did a round cake, forming it in circular sponge tins just larger than the 16cm pastry ring I used to cut the sponge circles. I coated the cake in creme mousseline which was a bit of a mess. I would try tempered (white?) chocolate next time.

Ingredients

for the sponge

2 batches of joconde sponge mix - in total

2 x 185g icing sugar

2 x 185g ground almonds

2 x 5 eggs (250g), plus 5 egg whites (150g)

2 x 25g caster sugar

2x 40g butter, melted and cooled

2 x 50g plain flour

for the filling

1 batch of Creme Mouselline

6 egg yolks

125g caster sugar

40g plain flour

500ml milk

1 vanilla pod

250g unsalted butter, cut into cubes

chocolate for coating - see preamble

Method

1. Make the sponges. Make the sponge mix as per recipe. Each mix quantity is for 4 sponge circles of approx 16cm. We need seven layers. If cooking in rectangular tins then more mix may be needed - or make a smaller diameter or a rectangular cake. If using the circular sponge tins, each layer requires a generous 200ml of mix. Take a potion of mix, add food colouring and colour using one of the rainbow colours - indigo, blue, light blue, green, yellow, orange and red. Put in the lined sponge tin. Bake at 200℃ for 4-5 minutes until the top of the sponge is no longer wet and sticky. Remove from oven and remove from tin and cool on a cooling rack - leaving the greaseproof lining paper intact. Repeat for the other 6 colours.
2. Make the creme mousseline. Make the creme mousseline as per recipe.
3. Assemeble. When all 7 layers have been baked and cooled, and the creme mousseline has been made we can assemble. Neaten up the baked sponges by cutting out circles using a suitable sized guide - a pastry ring in my case. You can also use a bespoke make template made from cardboard. Place the indigo layer on a cake board. Pipe some creme mousseline on the sponge. Add the next layer (blue) and press down lightly so that the cream spreads between the two layers. You are aiming for creme layers slightly thinner than the sponge layers. Repeat with the other coloured layers in turn.
4. Coat. Coat with more creme mousseline. Or better, tidy up the sides of the cake and chill the cake for ½ hour while you temper some chocolate which gets poured over cake to form a thin layer.

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