Lindt Flourless Toffee, Date, And Hazelnut Cake

Cake
Preheat oven of 325ºF (170°C). Grease a 9 or 10 inch (23 or 24 cm) springform pan and line the bottom with parchment paper.
Roast the 2/3 cup hazelnuts in a shallow pan for 8-10 minutes; remove from oven and put on a kitchen towel. Fold towel over the nuts and allow to steam for 5 minutes. Rub vigorously in the towel. This procedure will remove most of the skin. Chop the nuts and set aside.
Remove the pits from the dates and place them in a saucepan with the water, liqueur, and vanilla bean or extract.
Simmer over low heat until the dates are soft; remove the vanilla bean. Remove the saucepan from the heat and push the mixture through a coarse sieve, creating a smooth puree. Set aside to cool.
Beat eggs, yolks, salt, and brown sugar until the mixture is light and fluffy.
Place the butter in another saucepan and melt over medium heat. Add the chopped chocolate. Remove from heat and stir until the chocolate is completely melted and the mixture is smooth.
Mix the chocolate and butter into the whipped egg mixture. Fold in the date puree and ground hazelnuts, ensuring that there are no lumps. Mix until well incorporated.
Stir in the chopped hazelnuts.
Pour the batter into the prepared springform pan and smooth the top with the back of the spoon.
Bake 40-50 minutes or until done (check with toothpick).
Allow cake to cool in pan. Remove and top with chocolate ganache.
Chocolate Ganache
Place the chopped chocolate in a heat-proof bowl.
Combine the cream, sugar and syrup in a saucepan and bring to a boil over medium heat.
Pour the hot liquid over the chocolate and stir until smooth.
Stir in the butter.
Cover the ganache with plastic wrap (make sure the plastic makes contact with the surface of the ganache) and set aside to cool.