Chop the chocolate, melt it on a hot water bath, let it cool down a bit. Cream butter, 200 g sugar and salt with the whisk of the hand mixer. Stir in the eggs one by one. Mix flour and baking powder. Alternate with the milk and stir in briefly.
Halve the dough. Stir melted chocolate and 100 g hazelnuts into 1 half of the dough. Fold 75 g hazelnuts into the other half. Grease a cake tin (approx. 2 litres capacity) and sprinkle with ground hazelnuts. Alternately fill in the dough by the spoonful. Pull through with a fork. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 1 hour. Allow to cool slightly, turn out of the tin and let it cool completely. To decorate, melt 2 tablespoons of sugar in a pan until golden brown. Turn 2 tablespoons of hazelnuts in it.
Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 1 hour. Allow to cool slightly, turn out of the tin and let it cool completely. To decorate, melt 2 tablespoons of sugar in a pan until golden brown. Turn 2 tablespoons of hazelnuts in it. Place on aluminium foil and leave to cool. Dust the ring cake delicately with icing sugar and cocoa. Decorate with the caramel nuts