Pre-heat the oven to thermostat 7 (210°C).
Make a cut in each chestnut using the tip of a knife.
Immerse the chestnuts in boiling water for 4 to 5 minutes, drain and peel.
Add all the ingredients for the dough to a bowl, mix and knead to form a dough.
Grease a flan dish for 8 people with 1 tablespoonful of Lesieur Sunflower Heart oil and press the dough into the dish.
Pour 2 tablespoonfuls of Lesieur Sunflower Heart oil into a saucepan and gently fry the chestnuts for 2 to 3 minutes.
Sprinkle in the flour, sugar and vanilla sugar, pour in the milk and bring this mixture to the boil.
Mix well.
Arrange the Brocciu on the tart base.
Pour in the chestnut preparation.
Bake in the oven for around 20 minutes.