Cream together butter & sugar with electric whisk, until pale & fluffy. Beat eggs in a separate bowl. Add a bit of flour and a bit of egg in stages, folding lightly in with the creamed mixture. Don't just chuck it all the eggs and flour in at once, this will separate the mixture, and you want to retain as much air as possible from the whisking!
Once folded, pour/spoon mixture into baking tray(s), and bake for 30 mins! Leave to half cool on cooling racks, then add a thick layer of jam, cut & serve whilst still warm! Yummy!