Scoop ice cream into 21/2-inch balls.
Lightly roll in cookie crumbs.
Cover and freeze until firm.
Combine chocolate and butter in top of a double boiler; bring water to a boil.
Reduce heat to low; cook until chocolate melts.
Stir in milk and sugar.
Cook, stirring constantly, until sauce is thickened and smooth.
Arrange ice cream balls in individual serving dishes.
Garnish with whipped cream and cherries, if desired.
Spoon warm sauce over ice cream balls just before serving.