1 ounce cognac*
1/2 ounce lemon juice
1/2 ounce simple syrup
2 ounces Champagne
(any dry sparkling wine will do)
1 lemon twist

Shake cognac, lemon juice, and simple syrup with ice.
Strain into a chilled cocktail coupe or flute.
Top with chilled sparkling wine. Garnish with lemon twist.

*Most bartenders will make Anglicized French 75s with gin,
but the bartenders who matter insist that cognac is more
appropriate (and tastes better) in a French-American cocktail.