Quickly chill a champagne flute or wine glass in the freezer.
Juice a quarter of the lemon and cut several thin slivers of peel. Reserve.
Fill a cocktail shaker with ice and pour in the St. Germain and lemon juice. Give a quick shake to chill.
Retrieve your chilled glass and pour in the contents of the shaker.
Top the St. Germain & lemon juice mix with 4 ounces of champagne.
Garnish with the lemon peel, edible flowers, or slightly bruised basil leaf for a fantastic herbaceous variation.