Add the hot cocoa mix, marshmallow crème, and whipping cream to a medium bowl. Begin beating with an electric mixer on low speed, then increase to medium after the ingredients are combined, continuing to beat until stiff peaks form. Drizzle chocolate syrup along the insides of two glasses or mugs. Fill each glass halfway with ice. Pour 1 cup of milk into each glass. Place the whipped cocoa into a piping bag or a plastic zip closure bag with a corner cut out. Pipe the whipped cocoa on top of the milk. Finish by adding your favorite garnishes, such as graham cracker crumbs, chocolate chips, and mini marshmallows.