LINE 9 x 5-inch loaf pan with aluminum foil, extending foil over sides of pan. Combine cookie crumbs and butter; press firmly into bottom and halfway up sides of prepared pan.
BLEND 1/4 cup peppermint candy and water in blender until candy dissolves.
COMBINE sweetened condensed milk, food coloring, if desired, 1/2 cup crushed candy and peppermint liquid; mix well. Fold in whipped cream and remaining 1/4 cup crushed candy. Pour into prepared pan. Cover.
FREEZE 6 hours or overnight. To serve, remove from pan; peel off foil and slice. Garnish as desired.