Place the biscuits ten centimetres (four inches) apart on a plate. Top each biscuit with a spoonful of blackcurrants.
Place the egg whites into a clean bowl and whisk until stiff peaks form when the whisk is removed. Gradually add the sugar, whisking between each addition, until the mixture is thick and glossy.
Place a scoop of ice cream on top of the blackcurrants on each of the biscuits. Pipe or spread enough of the meringue mixture to completely cover each biscuit. Sprinkle the meringue mixture with caster sugar and the finely chopped ginger.
Use a mini-blowtorch to brown the meringue all over. Alternatively, place the biscuits onto a baking sheet and bake in the oven at 230C/450F/Gas 8 for 5-6 minutes.
To serve, place the Baked Alaskas onto plates and serve immediately.