Seven Layer Rainbow Cake

Seven Layer Rainbow Cake

(adapted from Raspberri Cupcakes)
355g plain flour
1 tbsp baking powder
1/2 tsp salt
225ml milk
2 tsp vanilla extract
400g caster sugar
225g butter, softened
4 eggs
Food colouring

Preheat oven to 180ºC and grease and line your tins. I only had 2 round tins, so had to bake this in batches. Combine flour, baking powder and salt in a bowl and set aside. Mix milk and vanilla together in a measuring jug and set aside. Using an electric mixer, beat sugar and butter in a large bowl until pale and creamy. Add eggs one at a time, beating well after each addition. Add flour mix and milk mixture, beginning and ending with flour mixture (Add 1/4 of the dry mixture followed by 1/3 of the wet mixture at a time). Beat until smooth, occasionally scraping bowl with a spatula. Divide mixture evenly into 7 bowls and add a different colour of the rainbow to each bowl. Pour batter into prepared tins and bake each layer for about 10 minutes or until a skewer into the centre comes out clean. They're very thin layers so keep a careful eye on them. Cool on a wire rack. 

Vanilla Buttercream
150g unsalted butter, softened
225g icing sugar
2 tbsp hot water
1 tsp vanilla extract

Beat the butter until light and fluffy. Add in half the icing sugar, half the water and the vanilla. Beat until combined. Add in the remaining icing sugar and water (if needed). Beat until combined.