To Whom It may Concern:
_____ has worked for me over the past _____ years. He has been an invaluable employee, and every day I learn more from him than he learns from me. In fact, without him I could not possibly run this business and I do not want to let him go, but he says that it is time for me to try and fly on my own. He is honestly the most intelligent person I have ever met in my life and I wish that my own children will someday be half as good. In fact, I have been trying to get ____ to father children on my wife so I can raise kids even half as intelligent as he is.
Sincerely
_______
Boss of ____, but really his day-to-day assistant.