This is another classic cocktail, made with crème de cassis (blackcurrant liqueur) and Champagne. Again, any dry sparkling wine will do the job. You don't want it to be too sweet, so just add 2 tsp to the base of your Champagne flutes, then top up with fizz. Crème de mûre (blackberry liqueur) is another really lovely option, as is raspberry liqueur, like Chambord.