How to Make It
Place chocolate in a medium mixing bowl. Bring cream to a boil in a small saucepan over medium-high heat. Pour cream over chocolate and stir until smooth. Stir in sparkling water and Cognac.
Refrigerate until chocolate mixture is firm enough to roll into 1-inch balls, about 11/2 hours. Roll each ball in sanding sugar. Cover and refrigerate truffles at least 30 minutes or up to 3 days before serving.