Using kitchen towel, grease silicon moulds lightly with unflavoured oil to make eggs easier to remove.
Break chocolate into small pieces and melt in a double boiler (or saucepan on a VERY low heat again) on the stove, stirring frequently. Remove from heat.
Using a pastry brush, coat the inside of each mould evenly with melted chocolate.
With a flat knife, scrape across the edge of each mould immediately after coating it to give a flat finish (this will make it easier to join egg halves together later on).
Place moulds in freezer for 10 minutes to set chocolate, meanwhile return remaining bowl of chocolate to double boiler to ensure it stays melted.
Repeat process, building up 3-4 layers of chocolate on each mould and leaving eggs to set in freezer for 5 minutes between applying each layer - the chocolate will set more quickly now because the moulds have already been in the freezer. (Pay special attention to building up a slightly thicker layer of chocolate around the edge of each mould so eggs are less likely to crack when sticking them together.)