Preheat oven to 170°:C (150°:C fan-forced) and grease a 26cm springform tin.

Place dates in a saucepan along with water, Frangelico and split vanilla bean.
Simmer over a low heat until dates are soft. Remove from heat and push dates through a coarse sieve, creating a smooth purée. Set aside to cool.

Using an electric mixer, whisk eggs, egg yolks, salt and brown sugar until mixture is light and fluffy.

Place butter in a saucepan and melt over a medium heat. Break up chocolate and place in saucepan with the butter. Remove from heat and stir until chocolate is melted and the mixture is smooth.

Mix the chocolate and butter into the whipped egg. Fold in date purée and hazelnut meal, ensuring there are no lumps. Mix until well incorporated and fold in hazelnuts. Pour cake batter into greased tin and smooth top with the back of a spoon.

Bake for approximately 50 minutes or until cooked. Allow cake to cool in the tin. When cool, remove and top the cake with ½ recipe of plain ganache.