for 9 inches I would use the following recipe
350g caster sugar
350g unsalted butter or stork
5 eggs
350g self raising flour
2tsp vanilla extract
grease and line your pans and preheat oven to 175c
beat the butter and sugar together well until pale and creamy,
beat the eggs together in a bowl and gradually add to the mix, letting each bit mix in before adding more so it doesn't curdle,
fold in the flour and add the vanilla extract
It should be a fairly thick consistency, one that drops of the spoon with a good shake.
Bake in the oven until cooked through, to test if it's cooked a put thin metal skewer in the middle, if it comes out clean it's done, or press the top and if it springs back then it's cooked, should take about 45 mins
cool before decorating