I would like to share with you this recipe I found at dulcisinfurno.blogspot.com.
I used 3 eggs instead of 4 and a little less butter, and it came out wonderfully.
If you have guests, serve it with a spoonful of whipped cream or whipped mascarpone, and you’ll have them drool.
Ingredients (for a 10in cake pan):
2/3 cup sugar
8,81oz chopped hazelnuts
8,81oz pure chocolate
1 tablespoon icing sugar
In a saucepan, melt the butter with chocolate in a bain marie and continue stirring, until the chocolate has melted. Mix well the eggs with the sugar and chopped hazelnuts. Add gradually the chocolate mixture and mix well. Add the starch and vanilla, mix again. Transfer the mixture into a buttered and floured cake pan and bake in the preheated oven to 356°F for 50 minutes approx. Let it cool down and then remove it from the pan. Sprinkle with icing sugar and serve.
If you try it, let me know how you got on!