First, we prepare a short pastry without butter. In a bowl, dissolve the sugar in the water. Also, add the vanilla bean seeds and the oil.
Mix to create a sort of emulsion to which only lastly add the sifted flour with cocoa and baking powder.
Stir quickly with a spoon, then transfer the mixture to the pastry board and finish working it.
Give it the shape of a loaf, wrap it in plastic wrap and put it in the refrigerator for at least two hours.
In the meantime, prepare the chocolate custard because it must be very cold when you fill the cake. In a deep bottomed pan, often mix the sugar, cornstarch and bitter cocoa. Pour the vegetable milk flush, stirring with a whisk so that no lumps form, then transfer to the heat.
Cook over medium heat, stirring constantly until the cream begins to thicken. It will take about 5-10 minutes.
Finally, add the coarsely chopped dark chocolate and stir until it has melted. Transfer it to a bowl and cover it with cling film. Now take the shortcrust pastry and with the help of parchment paper, roll it out to half a centimetre thick. Coat a tart mould with a diameter of 24 cm, removing the excess edge. Prick the bottom with the teeth of a fork, then cover it with a sheet of parchment paper.
Pour over the dried chickpeas, raw rice or the special weight balls, and cook at 180° C for 20 minutes.
Once out of the oven, let it cool and fill with the custard.