Preparation method
For the base, line the base of a frame with a sheet of greaseproof paper, then cut the hazelnut sponge to the exact size of the frame. Place into the fridge to retain moisture in the sponge. Meanwhile, for the Délice, heat the milk and cream in a saucepan and heat gently over a medium heat until it just reaches boiling point. Meanwhile, whisk the eggs in a bowl. As the milk and cream mixture comes to the boil, pour it over the eggs, and then whisk the mixture constantly until smooth and thick. Stir in the chopped chocolate and whisk again until the chocolate has melted and the custard is smooth. Remove the sponge base from the fridge and pour in the chocolate Délice preparation to fill the mould. Gently tap the sides of the mould to release any trapped air bubbles, then smooth the surface using a palette knife. Chill in the fridge for 6-12 hours, or until completely set. Meanwhile, create the candied pistachio nuts. Preheat the oven to 180°c. Toss the pistachios with just enough warm water to make the nuts slightly sticky. Add the brown sugar and salt to taste. Return to the oven and bake for 30 minutes. Cool. The nuts should be totally dry and crunchy after cooling. If not, return to the oven and bake longer. Store tightly covered.
For the chocolate rock sugar, place the sugar and water to boil in a heavy based saucepan and leave to soak for 10 minutes before bringing to the boil and skimming off any surface impurities. Boil the sugar to 138°c and remove from the heat and halt the cooking process. Mix the cocoa powder with the royal icing and stir into the molten sugar quickly. The sugar will now change colour and increase in volume. Quickly pour this into a baking tray lined with silicone paper to cool down and set. Leave to dry out for 12 hours before using.
For the coffee foam, just before serving, heat half of the coffee in a pan until just hot but not boiling. Squeeze the soaked gelatine sheet dry, then add it to the hot coffee and continue to warm until the gelatine has completely dissolved. The gelatine will stabilize the foam and will help it last longer on the presented plate. Pour the remaining cold coffee into a bowl, and then add the hot coffee mixture to it. Whisk well until the mixture starts to foam.
To serve, heat the outside of the mould using a chefs' blow torch to loosen the base of the Délice. Carefully remove the pastry frame from the Délice. Heat the top of the Délice very quickly using a chefs' blow torch to make the surface glossy and slice into portions as required.
Serve with the following accompanying garnishes. Chocolate decoration Candied hazelnuts or pistachio nuts Cremeaux Délice Pistachio ice cream Chocolate rock sugar Coffee foam