Combine vodka and St. Germain in a gallon jug. Immediately before serving, add the sparkling wine and transfer the mixture to a serving container. Serve over ice with bitters nearby – add about 4 drops per glass (more or less based on preference, but I like 4!).
Serves 20 (in a rocks glass filled with ice).
By Kate Bolt, #livinglark – To buy a copy of Kate’s new book Lark Cocktails, go to LivingLark.com