In a bowl, mix the yolk with the sugar. Add flour, vanilla, a little rum and melted butter. Mix well. In another bowl, beat the egg whites with a mixer. Gently fold into the mixture using a pastry blender. Pour the dough onto a baking sheet lined with baking paper. Bake for ten minutes at 180°C. The cookie should come out golden-brown. Remove the cookie from the oven and allow to cool completely before cutting with a cookie cutter to fit your mold. Set aside until ready to assemble.
In a bowl of cold water, soften the gelatine leaves. In a saucepan, heat 40g liquid cream with the chestnut cream. Off the heat, add the wrung-out, softened gelatine. Mix well. Set aside. Using an electric mixer, whip the remaining 110g of cold cream. Gently fold in the cooled mixture.
Assembly
Fill mini raggio mold halfway with chestnut mousse.
Poach chestnut cream.
Top with the remaining chestnut mousse and finish with the vanilla cookie soaked in syrup (water, sugar and a little rum). Place in the freezer overnight.
The next day, remove the frozen entremets from the moulds and immediately apply the brown velvet spray. Chill for at least 3 to 4 hours, until defrosted, before serving.
Mix all ingredients. Line tile mold. Smooth with an angled spatula to remove excess. Bake in a hot oven at 170°C for 6-8 minutes (depending on your oven). As soon as removed from the oven, unmold. Be careful, they harden very quickly and become brittle. Handle with care.