Preheat the oven to 170C and prepare a cookie pan covered with parchment paper.

In the bowl of your standing mixer, cream the butter and sugar until they are light and fluffy.

Add the vanilla, pinch of salt and egg yolk and combine until fully incorporated.

Sift in the flour and once it's all combined, roll the cookie dough into a log and slice 6 pieces, roughly 0.5cm thick. 

You can freeze the rest or bake, but as for the other 6, bake them for 15 minutes or until golden. Let them cool fully.

While the cookies are cooling down, prepare the chestnut paste: boil the chestnuts until soft and peel them. 

In a small pot add the crushed and peeled chestnuts (you should have roughly 250g of cooked chestnuts), milk (it has to be the same weight as the cooked chestnuts), sugar and vanilla extract. Cook them on low until all the milk has been fully incorporated, making sure you keep on mixing using a spoon. It will take roughly 20-25 minutes.

Once cooked, blend it until smooth and set aside to cool down slightly.

Whip your cream with the icing sugar until stiff peaks form, then move it into a piping bag.

Place the 6 cookies on a tray, then pipe some whipped cream to create a mountain and, using a potato ricer, place the chestnut puree over the whipped cream so that they resemble miniature mountains. Repeat until all 6 cookies are done.

Decorate with a dusting of icing sugar or cocoa powder and an optional marron glacé if you have.