How to prevent oneself from eating the whole bar of chocolate at once? I suggest you build a telegraph key using the chocolate as raw material.
First cut the bar into suitable pieces for the key shaft, its support and the base. Make sure the room temperature is not too hot or the chocolate becomes soft. Too much hand contact is bad for the same reason.
A chocolate egg could be used as a key knob, but there is a serious risk of sticky fingers. A wooden knob is much more practical.
Make the necessary holes in chocolate with an ordinary power drill or whatever. Put a wooden plate under the chocolate base and use suitable screws.
Be careful with the key shaft. It will break if the gap between contacts is too wide and if too much force is used when keying. (That accident happened to me in the SCAG Straight Key Day, June 2011.)
A mouthwatering sweet video clip can be seen here: