Chill 4 tall Pilsner glasses in freezer until ready to serve.
Combine sugar and 1 cup water in a saucepan over high heat, stirring until sugar dissolves. Cool, and add vanilla extract. (Can be made ahead up to this point and stored in the refrigerator up to 1 month.)
Pour 3 tablespoons sugar syrup into each glass, and top with 3 scoops of vanilla ice cream. Top with club soda. Garnish, if desired.