Melt butter in a large skillet; add shallots, and saute 2 to 3 minutes or until tender. Stir in champagne, and cook 7 to 9 minutes or until reduced by half. Stir in whipping cream, salt, pepper, and saffron; bring to a boil. Reduce heat, and simmer, stirring constantly, 5 minutes.
Pour sauce through a wire-mesh strainer into a bowl, discarding shallots and saffron.