Preheat oven 325F
Place the ham fat side up in a shallow baking dish, fat side up. Bake at 325F until meat thermometer registers 150F, about 14 minutes per pound.
Forty five minutes before the ham is done, remove it from the oven. Score the fat surface. Mix the brown sugar, mustard in a medium bowl to form a paste. Gradually add the ale and stir until combined. Brush part of the mixture on the ham. Return it to the oven to complete baking brushing frequently with the remaining beer mixture.
This is a beautiful example of Old Paris Green Pink Gold Pot de Creme Set which dates back to the late 19th century