Ingredients:
6 egg yolks
6 egg whites
9 oz. (250 g) caster sugar
9 oz. (250 g) butter
9 oz. (250 g) unsweetened baking chocolate
9 oz. (250 g) ground hazelnuts
1 tsp. vanilla extract

Preparation:

1. Preheat oven to 350 F (175 C).

 

2. Melt chocolate.

 

3. Whisk egg yolks with the sugar, butter and vanilla extract. Stir in the chocolate and hazelnuts.

 

4. Beat the egg whites until firm and gently stir into batter.

 

5. Pour 2/3 of batter into a buttered cake pan. Bake for 30 minutes.
   Put the remaining 1/3 of batter in the refrigerator (it is going to make the cream).

 

6. Let cool. Cut the cake in half lengthwise.

 

7. Spread half of batter cream on one disk. Cover with other disk. Spread the rest of the batter on the top.