2
Scrape the bottom and the sides, mix well. Return to the pan and cook over low heat, stirring continuously for 3 to 5 minutes. Cool to room temperature.", "Whip the cream and add to the cold custard. Cover with plastic film and chill.", "Cake: Pre-heat the oven to 350u00b0 F with rack in the middle position.", "Butter a rectangular baking tray. Cut a piece of parchment paper the size of the bottom of the tray and adhere it to the butter. Butter and flour the parchment paper and sides of the tray.", "Toast the skinned hazelnuts until golden brown, cool them completely and process them finely.", "Cut the chocolate in pieces and melt in a pan over a bain-marie. Remove the pan and put it on a cold surface to lower the temperature of the chocolate.", "Open the vanilla bean and scrape out the seeds.", "In a stand mixer fitted with the paddle attachment, beat the soft butter with the sugar and vanilla until pale and fluffy.", "Add the 6 egg yolks, one at a time, and the cooled melted chocolate beating well.", "Sift the flour, potato starch and the salt together and fold it in the above mixture. Add the ground hazelnut.", "Whisk the egg whites and half way through add the 2 tablespoons of confectioner's sugar and continue beating to hard peaks. Fold the egg whites in 3 parts in the cake mixture, very gently.", "Pour the cake mixture in the baking tray and smoothen the top so it bakes evenly. Bake for 25 to 30 minutes or until golden brown.", "Cool for 5 minutes in the pan and then invert on a wire rack and peel the parchment paper. Allow to cool completely before cutting.", "When completely cold, use a serrated knife to cut in rectangles or whatever shape you prefer.", "Assembling the cake:
