Rainbow Cake

1. Preheat the oven to 180 C / 350 F and grease and line the bottoms of two or three round cake pans, baking the layers in batches if you do not have enough pans.
2. Cream the softened butter and superfine sugar together with an electric mixer for 3 to 4 minutes until pale and fluffy, then beat in the eggs one at a time, adding a spoonful of the flour with each to prevent curdling.
3. Fold in the remaining flour, baking powder, and salt, then stir in the vanilla and milk until you have a smooth, soft batter that drops easily from a spoon.
4. Divide the batter evenly among four bowls and tint each one a different color with gel food coloring, stirring until the shades are bright and uniform.
5. Spoon each colored batter into a separate lined pan, smooth the tops, and bake for 18 to 22 minutes until the sponges spring back when lightly pressed and a skewer comes out clean, then cool completely on a wire rack.
6. Make the buttercream by beating the butter until creamy, then gradually adding the powdered sugar, milk, and a pinch of salt until light and spreadable.
7. Stack the cooled colored sponges with a layer of buttercream between each, then coat the top and sides with the remaining frosting and chill briefly before slicing to reveal the rainbow layers.

You'll use: Oven · Pan · Mixer