This is such a delicious cake; it lasts for days and is fancy enough to serve with some double cream and poached rhubarb for a pudding too.
Preheat the oven to 180°C and grease and line a 26cm cake tin with baking paper. Blitz the toasted hazelnuts into a fine meal and place in a bowl.
Break the chocolate into a small saucepan, add the butter and place over a medium heat and cook, stirring often until the mixture has melted together.
Remove from heat and stir in the coffee, flour and hazelnut meal.
Now, whisk the egg yolks and sugar together until pale then fold this into the chocolate mixture.
Whisk the egg whites until stiff peaks form. Very gently fold through the chocolate mixture then spoon into prepared cake tin and smooth the surface.
Bake for 35 – 45 minutes or until the cake’s centre is just firm/springy to touch.
Let cool in the tin then turn out to a wire rack to cool.