In a cocktail shaker filled with ice, combine the gin, simple syrup, and fresh lemon juice. Shake well.
In each flute, place one lemon twist. Evenly divide the gin mixture between the two champagne flutes and fill the empty portion of each glass with champagne or your sparkling wine.
Lemon Infused Simple Syrup
In a saucepan over medium heat, combine the sugar, water, juice of the half lemon and the rind.
Simmer until all the sugar dissolves. Turn off heat and let sit for 30 minutes.
Strain and chill the lemon infused simple syrup and store in the refrigerator for up to two weeks.