If your feeling creative try this -
Using a pin, poke a hole in the bottom of a large raw egg, insert the tip of a pointed knife, and turn to open the hole slightly. With a metal nail file smooth and widen the hole to around 1/2 inch.
Insert pin into the hole to pierce and "stir" the yolk. Hold the egg, hole down, over a bowl, and blow air into the hole with a rubber ear syringe, this will clear out the raw egg. Rinse out shell.
Sterilize eggs: Submerge them in a pot of cold water with 1 tablespoon white vinegar; bring to a boil, then simmer, skimming foam from surface, 10 minutes. Leave to drain on a board covered in kitchen towel for a couple of days.
Melt good quality dark chocolate in microwave until melted. Place eggshells in an egg carton. Place a disposable pastry bag in a tall glass, and fold top down. Fill bag with chocolate; cut tip to create a 1/4-inch opening.
For solid chocolate eggs: Insert tip of bag into each egg, and fill with chocolate. Let set completely, about 4 hours.
Alternatively, fill eggs with ganache: Fill all eggs with chocolate, then let stand 5 minutes instead of letting chocolate set. Pour chocolate out of eggs into a glass measuring cup, tapping your hand against cup to let most of the chocolate drain out (do not add to tempered chocolate). Let chocolate "shells" set completely.
Fill a disposable pastry bag with ganache (see below) cut tip to create a 1/4-inch opening. Insert tip into egg; fill with ganache. Tap egg gently, hole up, on a folded kitchen towel to eliminate air pockets; fill to top. Continue with remaining eggs. Refrigerate until set, about 4 hours. Ganache-filled eggs can be refrigerated up to 1 week; solid eggs can be stored in a cool, dry place until ready to serve.
Ganache
For dark choc ganache, use 2 cups heavy cream and 1 pound dark choc chocolate. For milk-chocolate or white-chocolate ganache, use 1 1/4 cups heavy cream and 1 1/4 pounds milk or white chocolate. Bring cream just to a boil, then pour over finely chopped chocolate into a medium bowl. Let stand 5 minutes; stir until smooth. Leave on side stirring occasionally, until cool enough to pipe (usually an hour or so)
Once filled these are nice and hard for decorating the shells.