Roughly chop the chocolate. Separate eggs. Whisk the egg yolks, sugar and salt with the whisk of the hand mixer until thick and creamy. Stir in orange juice and oil. Mix flour, baking powder, hazelnuts and chocolate and stir in. Beat egg whites until stiff and fold in.
Grease the mini-bowl cake tin (12 troughs of 80 ml capacity each) and sprinkle with flour. Spread the dough evenly into the bowls. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for 15-18 minutes. Let the cakes cool down for about 5 minutes. Turn out of the tins and let them cool down on a cake rack. Dust the cake with icing sugar and decorate with orange peel and mint