Melt 375g of the chocolate in a double boiler, stirring constantly. Using a sugar thermometer, bring the chocolate to 48 degrees C for dark chocolate or 45 degrees C for milk chocolate. Remove from heat.
To temper the chocolate, add in the remaining unmelted chocolate. Stir well, until smooth. When the chocolate reaches 32 degrees C for plain chocolate or 30 degrees C for milk chocolate, it's ready to use.
Using a pastry brush, paint egg moulds with melted and tempered chocolate till covered. Chill for 10 minutes in the fridge. Brush again with chocolate, then chill again for 10 minutes. Finally, brush a third time and chill for a final 10 minutes.
Carefully unmould the egg halves and trim the edges with a sharp knife. Brush the edges with a little melted chocolate, then carefully bring two halves together to form a single egg. Carefully set back in the mould and chill for 10 to 15 minutes, or until set.
Tempering the chocolate isn't necessary, but it will prevent your chocolate egg from 'blooming', that is, turning a matte, greyish colour after a few days. Tempering ensures your chocolate egg will be shiny and look that little bit more professional!