Cream together the butter and sugars until light, then beat in the egg. Fold in the flours and baking powder then finally fold in the chopped chocolate. Scoop out into small balls onto a tray and freeze for 30 minutes. Place onto baking trays spaced well apart and bake in the oven at 200`f for 10-12 minutes. Remove from the oven and immediately use a cookie cutter to form into neat rounds. Allow to cool down completely before decorating with glaze icing, coloured sprinkles and chopped mini eggs.