Melt the chocolate over a pan of simmering water. When it is melted, spread it thinly over the underside of a plate, or any other flat surface, so that the surface area is about 6 inches and 1/4 inch thick. Put in the fridge for 45 minutes to cool. When it is set, using either a cheese slice or a sharp knife, drag the blade across the chocolate so that it forms small curls. To decorate the cake place small rings of these curls around the clake to resemble nests and finish with a few mini eggs in each.