What unique ingredient is added to a Kir Royal?

The unique ingredient added to a Kir Royal is Chambord. This cocktail is a variation of the classic Kir, which typically consists of dry white wine and crème de cassis, a raspberry liqueur. In the case of Kir Royal, sparkling wine, usually Champagne, is used instead of white wine, and Chambord—a raspberry-flavored liqueur—is the delightful addition that gives this drink its distinctive and rich berry flavor.

Chambord is known for its deep berry taste and subtle hints of herbs and spices, which complement the effervescence of the sparkling wine beautifully, making it a popular choice for celebratory cocktails. Its presence transforms the drink into a more luxurious experience, which is fitting for the occasion often associated with a Kir Royal.

The other choices, although popular liqueurs, do not serve the same purpose or provide the same flavor profile as Chambord in a Kir Royal.