Wenneker Creme de Cassis Liqueur Wenneker Creme de Cassis Liqueur Wenneker Creme De Cassis is a sweet, highly concentrated, blackcurrant liqueur which is ideal with Champagne to make the famous Kir Royale. Because of it's high quality & fantastic flavour, Wenneker Creme de Cassis Liqueur can also be used as a base for a number of other cocktails.