Preheat the oven to 210°C. Butter 8 metal dariole moulds and dust each very lightly with flour.
Melt the chocolate, butter and brandy in a bowl set over simmering water, then leave to cool to room temperature. In a separate bowl, beat the egg yolks and sugar together until they are pale and doubled in volume.
Whisk the egg whites to stiff peak stage and gently fold into the egg yolks. Fold in the cooled chocolate (it must be at room temperature, or it will harden) until evenly combined.
Pour into the dariole moulds and bake for exactly 9 minutes. The puddings should be firm on the outside and still undercooked in the centre. These chocolate tortino are very rich and really just need a little whipped cream on the side. If you prefer, you could also serve them with vanilla ice-cream or a light custard cream.