Grease and line cake tins with parchment paper. Cream the butter and sugar until lightly and fluffy. Add all the eggs at once and beat well.
Sift the flour and baking powder together and add to the butter mixture along with half the milk. Continue to beat well (the batter with be doughy). Add the remaining milk along with the vanilla extract.
Pour into the greased tins and bake for 1 hour; reduce the heat to 180c/Gas 4 and cook for a further 15 minutes until cooked. A skewer into the centre of the cake should come out clean.