Combine Cognac, simple syrup, and bitters in a cocktail shaker with ice. Shake and strain into a champagne flute and top up with sparkling wine.
For those of you who don't know, the traditional Champagne Cocktail is a bitters-soaked sugar cube in a flute filled with sparkling wine. I'm not a fan of using a sugar cubes in drinks, especially one that has sparkling wine. First, who keeps sugar cubes these days, I know I don't. Second, the rough texture of the sugar cube gives the drink a lot of nucleation points and causes the drink to fizz and go flat quickly.
I chose to use simple syrup because it's something you'll have on hand or be able to make in no time. I also added some Cognac to bump up the alcohol content of the cocktail. This drink is great to make for brunch or in the evening to share with friends.