In a dish in a water bath, mix the eggs, honey, oil, baking soda, sugar and stir vigorously until the sugar melts. Then add the flour and stir until you get bubbles. Remove the mixture from the heat and divide it into 2 bowls. Mix one with the cocoa until homogenous.
Add enough flour to both bowls to be able to knead a smooth dough that can be rolled. Roll out 3 identical layers from the brown and white dough – 6 in total. Bake them in a tray, covered with baking paper in a moderately heated oven, taking care not to burn them.
For the cream, beat the eggs with half of the sugar in a water bath until you get a smooth and fluffy cream. Leave it to cool and separately beat the butter with the remaining sugar. Combine the butter and yolk creams carefully until you get a smooth cream. Finally, mix it with the ground hazelnuts.
Stick the layers together with thus prepared cream, alternating between brown and white layers. Coat the entire cake’s top with cream and then add melted couverture chocolate. Let the cake sit for 24 hours before you serve it.