1. Mix the gelatine with the water and allow to swell for about twenty minutes.

2. Toast the hazelnut powder on a baking tray for 15 minutes at 150°C.

3. Whisk the whole eggs and yolks.

4. Sieve the cornflour and icing sugar, then add the whisked eggs, together with the hazelnut powder, cream and vanilla extract.

5. Pour into a 56x9cm tray and bake for 18 minutes at 160°C in a preheated oven.

6. Toast the hazelnut powder on a baking tray for 15 minutes at 150°C.

7. Using a spatula, cream the softened butter, flour, sugar, hazelnut powder and salt together.

8. Once the batter is consistent, spread it out on a baking tray lined with grease-proof paper and bake for 15 to 17 minutes at 150°C in a preheated oven.

9. Warm up the Gianduja, add the hazelnut praline, streusel and salt.

10. Spread the biscuit onto a 56×9.5cm tray and set aside.

11. Let the black lemon infuse in the water and lemon juice for 5 minutes.

12. Pour through a chinois strainer into a saucepan, add the sugar and agar-agar, bring to the boil and let it simmer for one minute.

13. Pour 220g into the tray and store in the fridge.

14. In a saucepan, bring the milk and glucose to the boil, add the gelatine, stir, and then pour over the Gianduja milk and mix together.

15. The final step is to stir in the cream until it is incorporated and then place it in the fridge for 3 hours.

16. Heat the milk and cream*, add the beaten yolks and cook like a crème anglaise at 85°C.

17. Add the gelatine, mix, and then pour over the Gianduja and blend with a hand blender.

18. Whip the cream** until you get a smooth texture, then fold it into the Gianduja ganache when it reaches a temperature of 30-35°C.

19. Place in a pastry bag and pipe 35g of Bavarian cream on the bottom of each mould.

20. In a saucepan, bring the cream and icing to the boil and then pour over the Gianduja and hazelnut paste.

21. Blend with a hand blender and use at a temperature of 35-40°C.

22. In a saucepan, bring the cream* and glucose to the boil and then pour it over the chocolate.

23. Blend with a hand blender, add the cream**, blend again and then place in the fridge.

24. Remove the mould, trim the edges and cut into 15 rectangles of 6.5x2cm. Pour the liquid into a pastry bag fitted with a tip and pipe 10g of the creamy mixture onto each rectangle.

25. Place in the freezer for 2 hours. Gently reassemble the Bavarian cream on the edges of the moulds, then place the insert in the centre.

26. Place in the fridge for 3 hours. Remove from the fridge, take them out of the moulds, place on a cooling rack, then glaze the pastries.

27. Pour the Chantilly Opalys into a pastry bag and finish by making a zig zag pattern with the whipped cream around the edge of each pastry.