In blender container, blend 1/2 cup candies on high speed until coarsely crushed.
Remove to waxed paper.
Blend remaining 1/4 cup candies but leave in the blender.
Add water; blend until syrupy.
In small bowl beat cream, sugar and vanilla at medium speed until stiff peaks form.
Slice cake into 3 layers.
Sprinkle bottom layer with 2 tablespoons peppermint syrup.
Spread 1/2 cup whipped cream over the cake; sprinkle with 1 tablespoon crushed candies.
Top with second cake layer and repeat the step above.
Invert top layer.
Sprinkle cut side with remaining syrup.
Place right side up on the cake.
Spread remaining cream on top and sides of cake, dusting sides with crushed candies.
Scoop ice cream into balls.
Place ice cream balls on top of cake.
Sprinkle with crushed candies.
Freeze until served.