Cream the butter and icing sugar together. Add the remaining ingredients and knead until the texture is completely even. Set aside in the fridge until completely chilled (about 2 hours).

Mix all the ingredients together in mixing bowl.

Mix the egg yolks and cornflour together. Heat the chestnut puree gently in a saucepan. Take a small quantity of the chestnut puree and pour it into the prepared mixture. Return it all to the pan and heat gently until it comes to the boil.Add half of the butter to the warm cream and cool for 3 hours in the refrigerator. Add the cream to the remaining softened butter and rum and mix with the mixer until fully combined. Use a piping bag with a fine nozzle.

Roll out the pastry thinly and use it to line a lightly buttered 20 x 20 cm square flan tin. Cook the pastry case at 150°C (thermostat setting 5) for about 15 minutes. Stop pre-baking when it has taken on a pale colour. Pour in the filling and return to the oven for a further 15 minutes. Remove from the oven and allow to cool. Arrange a few thin strips of fresh mango over your flan. Top with the chestnut cream. Made a hollow square of milk chocolate and place it on top. Decorate as you wish.