Prepare the dough for the tart: put the sifted flour and diced butter in the bowl of the food processor.
Mix enough to obtain a sandy consistency.
Then add the yolk and cold water little by little.
Mix everything well, then remove the dough on the work surface and knead for a few seconds.
It forms a disc that we cover with plastic wrap and refrigerate for 30 minutes.
Meanwhile, prepare the cremeux (delicious cream, fine, but firm chocolate): heat the liquid cream and milk in a saucepan over low heat.
Gelatin is hydrated with 2 tablespoons of cold water and set aside.
Mix the yolks with the sugar for a few minutes.
Pour over the yolk cream in a thin line and stirring the hot liquid continuously, then put everything back on low heat and mix until it thickens (about 2-3 minutes).
Put the thickened cream over the broken chocolate in pieces and mix until completely melted.
The gelatin is liquefied over low heat, then poured over the chocolate cream.
Let it cool to consistency.
Remove the tart dough from the cold, spread it with a rolling pin on the lightly powdered top with flour, then shape it, compact it well and remove its edges.
Sting from place to place, then cover with baking paper over which we pour special ceramic grains, rice, beans, etc.
Bake at 180 degrees for 40 minutes (after 20 minutes you can remove the grains and continue baking the simple top).
Leave to cool, pour the cremeux and level.
You can put on top a glaze prepared from 100/150 ml liquid cream and 100/150 g chocolate.
Refrigerate overnight and then decorate according to your imagination.