Elegant, sparkling St. Germain Champagne Cocktail features a simple combination of brut champagne, St. Germain liqueur, and a splash of fresh lemon juice.
Combine St. Germain and lemon juice in a champagne flute and add club soda.
Top it all off with champagne, pouring a little bit at a time because champagne bubbles rise rapidly. (Pour some and stop to let the bubbles recede, then pour it some more.)
Toasted Rosemary Garnish (optional):
Use a kitchen torch to gently torch some of the rosemary ends until aromatic.
Drop the toasted rosemary sprig into the champagne flute with the cocktail.