You would double the recipe and make it 5 times, storing in preheated thermoses.

Champagne Sauce
(Makes 1 1/4 cups)
1 tablespoon minced shallot
1/2 cup dry Champagne
2 tablespoons Champagne vinegar
1/2 cup heavy (whipping) cream
4 tablespoons unsalted butter, cut into small pieces
Salt and freshly ground white pepper to taste

Place the shallot, Champagne, and vinegar in a small saucepan over medium heat. Bring to a boil and cook to reduce by one third. Add the cream to the pan, and cook to reduce again by one third.

Remove the pan from heat but keep the burner on low. Whisk in the butter one piece at a time. Return the pot to the burner for a few seconds if the sauce cools too much to melt the butter. Season the sauce with salt and pepper, adding a minimum of salt since the prosciutto is salty. Strain the sauce through a fine-meshed sieve and keep it warm over hot water.