Take 2 piping bags or make them from greaseproof paper.
Place the large Easter rounded side up. Quickly heat the blade of a serrated knife then cut off the top of the egg.
Turn the egg upside down. Briefly heat the blade of a palette knife then flatten the point. Immediately stick the cut-off piece, larger side up, to the flattened peak. Set aside to harden.
Put the dark and white chocolate into 2 different bowls. Melt each of the chocolate in a bain-marie.
Fill up each of the piping bag with one of the melted chocolates. Use to draw any motif you like (leaves, butterflies, etc.) onto an acetate sheet. Place in the freezer to harden.
Line the large Easter egg with tissue paper. Fill with the small chocolate eggs.
Take the acetate sheet out of the freezer. Carefully remove the motifs using a palette knife. Briefly heat the blade of a knife then apply on several areas of the large egg surface. Stick the motifs over the melted chocolate, as fast as possible.