In a bowl over a double boiler add the chocolate and butter and leave to melt stirring occasionally.
In another bowl whisk the eggs and sugar.
Add flour and the crushed nuts in the egg and sugar mixture and mix well.
Add the chocolate to the flour mixture and mix well.
Pour the batter in a prepared cake pan line with parchment paper or in cupcake moulds .
Bake in a pre-heated oven at 170°C for about 45 mins .
Serve with chocolate mousse .