Cream together the butter and sugar with the essence.
When light and fluffy, stir in the egg yolks and lemon essence.
Add the flour, a little at a time and continue beating until the mixture forms firm dough.
On a floured surface roll out to 1/4" thick.
Using a 3" pastry cutter cut the dough and place them well spaced on a lightly greased baking sheet.
Bake for almost 12 minutes, when they should be lightly golden.
Remove onto a cooling tray and cool before serving.
Cream the biscuits together with mock icing which has been flavoured with a few drops of lemon essence.