Put water in a small pot. Set the stove to a medium low temperature. When water starts to boil, add raw drumstick to water, and let boil for 10 minutes.
While drumstick is boiling, take your eggs and two bowls, and separate the yolk, and the egg white. Ferrets should not eat egg white, because if ingested, this can result in hair loss.
After chicken is done boiling, take it out and let it sit to cool. Make sure not to turn your stove off yet. Your water should have some fatty oils floating on the surface. Now, take your egg yolks and add them to the water. Stir them around. You should have a goopy sort of substance floating around.
After your chicken is done cooling, cut it into small strips big enough for your ferret to chew, because you don't want them to inhale the soup. Add the strips to the soup, and mix around.
Turn off stove, and let the soup sit for about 5 minutes. Divide equally for your ferret(s) to enjoy.
Do not give this to your ferrets frequently. Remember this is a treat, not a meal, and if you give this to your pets regularly, it can make them sick. I recommend giving it to them when they are ill, or after they get out of surgery. If you want to give this as a treat, then I recommend giving it to them, once every 1-2 months.