1. Preheat the oven to 170?c / 325F / Gas Mark 3. Finely chop the hazelnuts and sugar in a food processor. Add the butter and process until moist clumps form. 2. Divide the dough between 4 x 10cm / 4 inch fluted loose bottom flan tins. Push the nut mixture evenly up the sides and across the bottom. Bake in the preheated oven for 45 minutes. Remove from the oven and cool. 3. Put the sour cream in a thick based saucepan and warm through. Add the chocolate. Remove from the heat. Stir until melted and smooth. Pour into the hazelnut crusts and leave in the fridge until set. 4. Put the blueberries and creme de cassis into a small saucepan, bring up to a simmering point. Turn the heat off and leave for a few minutes. 5. Remove the tarts from their casts and place on individual plates. Spoon the blueberries over the top and dust with a little icing sugar. NOTES : Chef:Amanda Grant