Preheat the oven to 180°C and grease and line two 20cm/8in sandwich tins.
Cream together the butter and the sugar.
Crack the eggs in one at a time, slowly adding some of the flour as well. Add the baking powder and mix well until everything is fully incorporated and you are left with a smooth mixture and lightly drops of the beaters when you lift them.
Divide the mixture between both tins and bake in oven for 20-30min or until risen and pale golden. They should be springy to the touch and come away from the edges easily.
Set aside to cool for about 10 minutes, then turn the cakes out of their tins and place onto a cooling rack.
When cooled, invert on cake layer onto a plate and spread with jam. It is optional to add a layer of whipped cream too. Then sandwich together with the second layer, top side up, and sprinkle with icing sugar.