Preheat the oven to 190℃ (170℃ fan)/375°F/gas mark 5. Grease and line a 26 x38cm (10x15in)Swiss roll tin with baking parchment.
Separate 4 eggs into two large mixing bowls. Weigh 125g (4oz) caster sugar then remove 2 tbsp and set aside. Add the remaining caster sugar to the egg yolks. Whisk until very thick, pale and mousse like.
Whisk the egg whites until standing in soft peaks. If you are using the same beaters wash well and dry between beating the egg yolk mixture and the egg whites. Whisk in the reserved 2 tbsp sugar.
Next, carefully fold 125g (4oz) ground almonds into the egg yolk mixture until just combined. Then fold in the whisked egg whites in two or three batches until just combined.
Pour the mixture into the prepared tin and spread level. Sprinkle over the flaked almonds. Bake for 12- 15 minutes until golden and springy to the touch. Remove from the oven and allow to cool.
Turn the cake out into a fresh sheet of prachment and carefully peel away the lining paper. Spread a generous layer of blackcurrant curd over the sponge taking it roght up to the long edges but finishing short of one of the shorter ends.
Starting from the opposite short end roll up like a Swiss roll. Transfer to a serving plate and lightly dust with icing sugar to serve.