Mix icing sugar, cake flour and hazelnut flour together. Whip up egg whites with sugar and incorporate the flours. Pipe discs onto flexipan and bake at 180°C / 356°F in a convection oven.
Melt the chocolate. Add the paste then the paillete feuilletine. Spread onto flexipan discs and freeze.
Heat all ingredients to 85°C / 185°F except the trimoline. Whisk until cool. Add the trimoline last.
Melt chocolate to 50°C-55°C / 122°F-131°F. Add some of the whipped cream. Fold in the pate a bombe. Fold in the rest of the whipped cream.
Boil the cream and add the gelatine and pour onto praline paste and hazelnut paste. While still warm fold in the pate a bombe. Fold in the whipped cream. Pour the hazelnut mousse into flexipan discs and freeze.
Boil and set aside.
Take 400 g of the boiled syrup. add 200 g glucose and the 700 g cream. Bring to a boil and pour onto the melted chocolate. Preserve in chiller and glaze at 28°C / 82.4°F on frozen cake.
In a filmed ring, assemble up-side down. Place the chocolate mousse in first. Add a layer of hazelnut dacquoise, then the hazelnut mousse followed by more chocolate mousse. Finish with a layer of the hazelnut crunch then the hazelnut dacquoise. Place in freezer. Glaze at 28°C / 82.4°F on frozen cake.