French Bastille Day Recipe: Modern chocolate flan

1. Détrempe: Melt 35 g butter in a saucepan. Place the flour, salt, water, vinegar and melted butter in the bowl of a stand mixer fitted with the dough hook. Mix at low speed until smooth, without overworking it.

2. Shape into a ball, score a cross in the centre, wrap in cling film and refrigerate 2 hours.

3.Turns: Roll the dry butter out on a sheet of baking parchment into a 16 x 20 cm rectangle. On a lightly floured work surface, roll out the détrempe into a 20 x 32 cm rectangle. Place the butter in the centre so that the two 20 cm sides touch the outer edges of the détrempe. Pull on the edges of the détrempe and fold them towards the centre to encase the butter.

4. On a lightly floured work surface, turn the dough 90 degrees. Roll the dough out into a 50 x 16 cm rectangle. Fold one third of the dough over itself. Then fold the other third over (first turn). Give the dough a quarter turn on the work surface. Roll out again to form a rectangle. Fold over one third of the pastry, then fold over the other third (second turn). Gently flatten. Put in the freezer for 20 minutes, covered with cling film.

5. Take the dough again, turn 90 degrees, repeat the previous operations (the two turns).

6. Put in the freezer for 20 minutes, then make a fifth turn. Cover with cling film and refrigerate for at least 24 hours.

7. Butter the 16 cm entremets ring and place on a baking tray covered with the Silpain® mat. Dust the work surface with flour. Roll the puff pastry out into a disc about 30 cm Ø and 3 mm thick, then line the ring with the dough. Refrigerate for at least 3 hours to prevent the pastry from shrinking during baking.

8. Preheat the oven to 170°C. Place a sheet of baking parchment, larger than the mould, over the pastry, add a layer of dried beans. Bake about 35 minutes, until the pastry is lightly golden.

9. Remove from the oven, remove the baking parchment with the dried beans and return the flan base to the oven for 10 minutes.

10. Bring the milk and cream to the boil. Remove the saucepan from the heat. In a bowl, whisk the egg yolks and egg with the sugar and scraped seeds from the vanilla pod until the mixture is pale and thickens, then stir in the custard powder. Pour in half the hot milk-cream mixture and mix well. Stir in the remaining milk-cream, then return to the pan. Cook gently, stirring constantly with a whisk until the cream thickens. Boil for 1 minute, stirring continuously. Remove from the heat and add the cocoa mass (liquor). Stir until smooth. Pour into a bowl, cover the surface with cling film, leave to cool.

11. Once cool, smooth with a whisk, then fill the pre-cooked flan base. Bake for 30 minutes at 170°C, leave to cool. Refrigerate for 3 hours, then unmould.

12. Oil the 14 cm entremets ring and line with baking parchment.

13. Cut the cold butter into 1 cm cubes. In a bowl, mix all the ingredients for the crumble until of sandy consistency. Spoon the mixture into the mould without packing too tightly. Transfer to a baking tray and bake for 20 minutes at 170°C. Leave to cool.

14.Unmould and dust the crumble with icing sugar. Carefully place the crumble on the flan.