Crème de Cassis
Crème de cassis is a sweet, deep red-purple liqueur made by macerating blackcurrants (cassis) in neutral grape spirit with sugar.
It is a historic specialty of the Burgundy region of France, particularly around Dijon, and is typically 15-20% ABV. Its bold, tart-sweet flavor is most famously paired with dry white wine or sparkling wine to make a Kir or Kir Royale. Beyond drinks, it's used to flavor sorbets, jams, and sauces, and pairs well with chocolate and cream.
Note the distinction: crème de cassis is the liqueur, not the blackcurrant fruit itself, which is also called cassis.