How to cook
Crack the eggs and beat them with a mixer along with the sugar. Add the oil, vanilla, milk and butter.
Stir and gradually add the baking powder, salt and flour. Mix the sponge cake layer mixture again with the mixer.
Pour it into a baking pan, which is lined with baking paper. Bake it in a moderately heated oven, until it is fully baked.
Here's how to make a sponge cake layer.