Preheat the oven to gas mark 4 or 180 degrees.
In a large bowl, cream together the butter and sugar. Gradually add the egg and self-raising flour while folding, until you have combined all the ingredients.
Add the zest and juice of 1 lemon, mix well then transfer the cake mixture to 9 cupcake cases.
Bake in the oven for 15-20 minutes, or until golden brown. Leave to cool for 10 minutes and prepare the drizzle.
Mix together the lemon juice and sugar to make a paste. Prick the top of the cakes with a skewer/cake tester making lots of small holes (so that the drizzle can pour right in!) then sprinkle with the lemon zest to decorate.