Start with a cold 8-10 inch skillet (non-stick skillet, or like chef Jacques, copper). Grease the skillet with a thin coating of butter. Add shallots, scallops, shrimp, mushrooms, Champagne, water and salt and pepper to the cold skillet. Put on the heat and bring to a boil. Reduce heat and simmer for 2 minutes. Remove from heat and strain out the scallops, shrimp and mushrooms and keep them warm.
Mix flour and remaining butter to form a paste. Return the stock (minus the seafood and mushrooms) to the stove ad bring to a hard boil. Reduce stock by 40%. Add the butter paste to thicken. Add cream and return to a hard boil, stirring until all flour is dissolved and sauce is thick and creamy. Return seafood and mushrooms to pan, bring to a boil and serve immediately
If I make this for an everyday dish I use margarine and whole or fat free milk, but for company I make it the FAT way!