Chocolate Hazelnut Dacquoise Cake

Directions

1. 1
   Preheat oven to 350°F. Line base and sides of 2 - 8 inch cake pans with parchment paper.
2. 2
   Whip egg whites to medium-firm peaks. Gradually add 1 1/3 cup sugar, beating until thick and glossy. Add vanilla and vinegar and beat for 20 seconds. Fold in ground hazelnuts. Distribute mixture between prepared pans. Bake for 35 mins, until pale golden and firm to the touch. Let cool in pans. Remove from pans and set aside.
3. 3
   Meanwhile, stir chocolate and 1/2 cup water over low heat until melted. Add remaining sugar and 3/4 cup water. Stir until dissolved. Simmer for 10 mins, until thickened. Remove from heat and let cool.
4. 4
   Whip cream to stiff peaks. Fold in 1/4 cup chocolate sauce. Spread over 1 hazelnut dacquoise. Top with remaining dacquoise. Cover and chill overnight, or for at least 1 hour.
5. 5
   Dust with powdered sugar. Serve cut into wedges and drizzled with remaining sauce.