Combine the egg yolks, 2/3 of the sugar and cinnamon in a small mixing bowl. Whisk until light and fluffy. Blend in the lemon juice and set aside. Whisk the Egg whites with the remaining sugar and a pinch of salt to stiff peaks. Pour the egg yolks over the egg whites along with the ground chocolate and ground hazelnuts. Carefully fold using a wooden or silicone spatula. Line a baking tray with parchment paper and grease it with butter or margarine. Pour the batter on the tray and spread evenly.
bake at 200 C without convection for about 25 to 35 minutes or until golden brown. Set on a cooling rack and remove the baking paper. If you have difficulties removing the baking paper, use a long knife and cut along the edge of the peel as you remove the it. Cool to room temperature
Vanilla Heavy Cream
Combine the heavy cream, sugar and vanilla sugar and whip to stiff peaks. Apply a thick layer using a piping bag. If you don't have a piping bag, simply spoon on and level.
set 1/5 of the chocolate aside and melt the remaining chocolate with the coconut oil over a slow simmering bermarie. Once fully dissolved take off the heat and add the remaining chocolate. Stir until dissolved. Dip the decorative hazelnuts in chocolate and set on a piece of parchment paper to dry.
Using a tablespoon, drip 1-2 full tablespoons over each slice. Allow the sides to drip a little. Once the chocolate has set, pipe three diagonal spots on each slice and top with chocolate dipped hazelnuts. Enjoy as fresh as possible.
You can add heavy cream to the chocolate ganache to make it soft otherwise it will remain brittle.