I am making sole in puff pastry for my New Year's Eve party. I have never made the tarragon cream sauce that I'd like to serve with it. I'd made Beurre Blanc in a cooking class, but that was under supervision and right before serving. This recipe is different and calls for lemons, juice, tarragon, parsley, white wine, shallots, garlic, cream, butter and seasoning. How far in advance can I make the sauce? Can I make it the night before and refirgerate it? Then reheat it in a double boiler? If not, how far into the recipe can I go, leave off the heat, then warm and add the butter right before serving? I want to enjoy my company during hors d'oervres.