Using a large, heavy skillet, bring butter, salt, pepper, sugar and water to a boil over high heat. Lower heat and slowly stir in Brussels sprouts and let simmer, partially covered and stirring occasionally, for 8-10 minutes.
Remove lid and turn up heat. Boil over medium-high heat for 4-5 minutes, or until water evaporates and Brussels sprouts are lightly browned.
Stir in half and half and turn up heat. Bring mixture to a boil, stirring frequestly. Reduce heat and add in chestnuts, letting simmer while stirring occasionally, about 3-5 minutes or until chestnuts are heated through.
Recipe by Tout va bien! (tm) at https://christymajors.com/a-very-downton-dinner/