How to cook
Sift the flour into a bowl and mix it with the sugar and salt. Cut the butter into small pieces and rub it with your fingers into the dry mixture to form crumbs.
If it is dry, put a spoonful of cold water and knead the butter crumbs into a dough.
Spread it in a cake tin with a removable bottom, about 70°F (20 cm) in diameter, in a thin layer. You can do this directly with your fingers, by making sure the base is flat, or by rolling it out between two layers of baking paper.
Refrigerate the base for 15 minutes, during which time preheat the oven to 360°F (180 degrees).
Bake the base for 20 minutes or until it aquires a pleasant color and then leave it to cool.
For the chestnut mousse, beat the cream with the powdered sugar and a cap of rum (add it at the end).
Put a spoonful of chestnut puree spoon by spoon and mix with smooth movements with a spatula, until a smooth mousse is obtained.
Spread it evenly on the base, crush 4 boiled chestnuts, so that the pieces sink into the mousse. Refrigerate it.
Make the chocolate layer by melting the butter with the chocolate and mixing it with the chestnut puree. Pour it over the mousse, flatten it out and allow it to cool.
For the chestnut toffee cream, put the butter, sugar and cream on a low to moderate heat and stir for 6 minutes. The temperature should not exceed 190°F (90 degrees). Add the puree and stir for another minute or two.
Put the gelatin to hydrate for 2-3 minutes in cold water, then strain it and put in the warm but not too hot toffee-chestnut mixture.
Pour it over the firm chocolate layer, wait for it to cool and store the chestnut cake for at least 2 hours in the fridge or even freezer.
To decorate the delicious chestnut cake, make figures from the melted dark chocolate, crushed or whole chestnuts - or whatever you imagine.
I made a mirror chocolate glaze with chocolate-covered chestnuts and added whipped cream roses. Even without the icing, the cake looks good, but I decided that at the last minute.
Cut and serve the chestnut cake well chilled.