Instructions

1. 1
   Preheat oven to 350°F and roast hazelnuts for about 15 minutes.
2. 2
   Rub to remove skin and allow nuts to cool.
3. 3
   Coarsely chop nuts and 2 ounces of chocolate into small chips and set aside.
4. 4
   Grease a 9x5-inch loaf pan with ½ tablespoon of the margarine and dust lightly with potato flour.
5. 5
   Place remaining chocolate, broken into small pieces, in top of double boiler.
6. 6
   Cover and place over simmering water until melted.
7. 7
   Gradually whisk in margarine until smooth and evenly mixed; set aside.
8. 8
   Whip egg yolks, while adding sugar slowly until pale and thick (about 10 minutes).
9. 9
   Pour in cooled chocolate, beating until thoroughly combined; set aside.
10. 10
    Whip the 5 egg whites at high speed until stiff.
11. 11
    With a rubber spatula, fold half the nuts, the chocolate chips and a quarter of the egg whites into the chocolate mixture.
12. 12
    Repeat with another quarter of the whites and the remaining nuts.
13. 13
    Reverse the process, pouring chocolate over the remaining egg-whites.
14. 14
    Gently fold the two mixtures together until uniform throughout.
15. 15
    Pour the batter into the pan
16. 16
    Bake in the center of the oven for about 55 minutes or until a cake tester comes out dry.
17. 17
    Allow to cool. Loosen sides with a knife before removing cake.