Line 25cm x 8cm (10" x 3") bar tin with aluminium foil, bringing foil up and over the sides; this makes it easy to remove the slice. Spoon softened ice-cream evenly over base of tin, freeze until quite firm.
Whip cream with sugar until firm, fold in brandy and creme de cacao. Spoon evenly over the firm ice-cream, return to freezer, freeze until firm. Cut into slices to serve. Top with whipped cream and grated chocolate or a strawberry.