Preparation of the butter:
Flatten the butter into a rectangle and place in the center of a rectangle of baking paper.
Close the rectangle of baking paper and spread the butter into a perfect rectangle.
Reserve in the cold for 15 minutes.

Making simple towers:
Dust the work surface with flour.
Roll out the dough to the same width as the butter and twice its length.
Coat the butter in the dough and make two simple turns.
Cover and refrigerate for 30 minutes.
Repeat to complete the third and fourth single rounds.
Let sit in the refrigerator for two hours.
Preparation of the pastry cream:
Divide the sugar into two parts.
Heat the milk with the vanilla.
Mix the eggs with some of the sugar and add the flour and baking powder.
Stir the hot milk into the eggs, then return to cook until thickened.
Add the butter and let cool.
Preparation of the white fondant:
Cook the water and sugar to 114 degrees.
Cool quickly and work the fondant until hardened.
Store at room temperature.
Assembling the mille-feuille:
Roll out the dough and cook it between two sheets of baking paper.
Let cool and cut into three equal parts.
Fill two parts with pastry cream and layer.
Make the cone with melted chocolate and garnish with white fondant.
Quickly ice the mille-feuille and let sit in the freezer for two hours.
Cut into equal portions and serve.
Advice :
Respect the resting time for the dough and the mille-feuille.
Quickly work the white fondant for the icing.
Use a serrated knife to trim the sides of the mille-feuille.
Practice icing on a sheet before making the mille-feuille.