Place the raspberries in the freezer. Put the flour, butter, cocoa powder and vanilla extract in a large bowl and rub together until it resembles fine breadcrumbs. Add the egg and bring together to form a dough. Wrap in clingfilm and chill for a minimum of 30 minutes.
Meanwhile, warm the double cream in pan. Add the chocolate just before it reaches boiling point and take off the heat. Stir continuously until all the chocolate is melted and well mixed. Set aside.
Preheat the oven at to 200°C/gas mark 6. Roll the pastry out to the thickness of a pound coin. Cut the pastry neatly to fit two 8cm round tart moulds. Cut off any excess pastry. Using a fork, prick holes all over the pastry. Cut out baking parchment to fit and place on top of pastry. Top with baking beans and bake for 18 minutes.
Take the pastry out of the oven, remove the beans and paper and bake again for another 8-10 minutes. Remove from the oven and mould and set aside to cool.
Stir your blackcurrant jam to loosen it. Spread the jam over the bottom of the pastry, then gently pour the ganache into each pastry case. Put in the fridge to set.
Place the sliced lime on a tray in the oven at 160°C/gas mark 3 to dry. Meanwhile, place the sugar in a frying pan on a low heat until the sugar is completely dissolved. Place the dried limes into sugar using tongs – be careful, as the sugar will be hot. Make sure the sugar fully covers the lime, then take out and set aside to set to harden.
Tip the chopped hazelnut into the remaining melted sugar and stir. Pour into a baking tray and leave to set. Once set, crush into tiny pieces. Sprinkle the hazelnut praline pieces on to your tart, dust with cocoa powder and top with the frozen raspberries and glass lime slices to serve.