Place half the cookie crumbs in an 8 x 8 baking dish. Place milk in top of double boiler; add marshmallows. Heat until marshmallows are dissolved; beat until smooth. Cool. Add peppermint extract. Whip cream; add to marshmallow mixture. Add any color food color if desired. Pour over crumb layer. Top with remaining crumbs. Cover with waxed paper; chill 24 hours.