Preheat an oven to 200°C.
Cream together the sugar and butter until they are light and fluffy.
Add both eggs and vanilla, and mix well.
Add all the flour and baking powder, and mix well.
Beat with wooden spoon in a circular motion, trying to incorporate as much air as possible.
Grease 2 round cake tins with butter.
Evenly divide the batter between the 2 pans—make sure the pans are no more than ¾ full.
Bake the cakes in the preheated oven for about 15 minutes until they are golden.
Cool the cakes in the pans, then unmold.
Spread the frosting and jam over one of the cake layers. Top with the other cake layer. Sprinkle well with the sugar of choice.