Pre-heat the oven to 180°C (350°F). Grease and line two 8 inch round cake tins.
Beat the butter and sugar together until light and fluffy (I used a stand mixer).
Add the eggs, one at a time, beating each one in before adding the next.
Sift the flour and baking powder together and then gradually add to the wet ingredients (I keep the mixer running). Stop working when the flour is just incorporated.
Split the batter evenly between the two pans and then bake for around 20-25 minutes, in the lower part of the oven, until the tops feel "bouncy" to the touch and an inserted skewer comes out clean.
Leave the cakes to cool in their pans for around ten minutes before turning out onto a wire rack.