1 cup Cognac or brandy
1 large vanilla bean, split lengthwise
1/2 cup creme de cassis (black-currant-flavored liqueur)
3 750-ml bottles brut Champagne
1. Pour Cognac into jar with lid. Scrape seeds from vanilla bean into Cognac; add bean. Seal jar tightly. Shake well. Let stand at room temperature at least 1 day. (Can be made 2 months ahead; refrigerate.)
2. Pour 1 teaspoon vanilla Cognac and 2 teaspoons creme de cassis into each of 12 Champagne glasses. Fill glasses with Champagne and serve.