Grease an 8" loose form cake tin,line the base & lightly flour.
To make the cake,melt the chocolate in a bowl over hot water.
In a separate bowl,whisk the eggs and sugar until light and foamy and the whisk leaves a trail across the mixture(approx.5mins using an electric whisk).Fold the melted chocolate into this using a metal spoon.Sieve the flour and cocoa together and fold gently into the egg and choc. mixture.Pour this into the cake tin.Bake in the centre of a pre-heated oven(350degF),for 25-30 mins,until it is springy to the touch.Cool the cake in the tin for 2-3mins,then turn it on to a wire rack to cool.Reduce the oven temperature to 225degF.
Draw two circles,8"diameter,on non-stick baking paper.Place these on a baking sheet.
Whisk the egg whites until stiff but not dry.Add half the sugar and continue whisking until the meringue stands in soft peaks.Sieve the cocoa and mix with the remaining sugar and ground hazelnuts,and fold this gently into the egg white.Fill in the marked circles with meringue.Bake in the centre of the oven for 1.3/4Hrs.Once cool,peel off the baking sheet.
Slice the cooled cake into 2 layers.
To make the icing,break the chocolate into pieces and melt in a bowl with the water over simmering water.Stir until smooth.Remove from the heat and allow to cool a little.Whisk the cream until it just stands in soft peaks.Gradually mix in the melted choc. and water.
Place a meringue on a cake stand and cover with some cream.Place a layer of cake on top and cover with cream.Repeat with the other layers of cake and meringue.
Spread the remaining cream over the top and sides of the torte and swirl using a pallette knife.Arrange chocolate curls on top and dust lightly with icing sugar.
Cut into wedges and serve with cream.