Heat the oven to 180讈/350F/Gas Mark 4. Beat the butter or spread with the sugar in an electric mixer for 3-5 minutes or until it is light and fluffy. One at a time lightly beat in the eggs with a tablespoon of flour then fold in the rest of the flour. Oil a loose 15cm (6inch) or 20cm (8 inch) cake tin (depending on whether you want your cake to be small and high or larger and flatter) or. if you do not have a loose-bottomed tin. line it with oiled nonsitck baking paper. Spoon the mixture into the tin and tap the cake tin gently a few times on the counter top to flatten out the top. Bake for 40 minutes or until a skewer comes out clean. Remove from the oven. allow to cool for a few minutes and then remove from the tin onto a rack and allow to cool completely. When the cake is cold. carefully cut it in half horizontally and spread a thick layer of jam over the bottom section. Carefully replace the top section and. using a sieve. sprinkle the top with icing sugar.