Sift the flour and cocoa powder into a large bowl then add the rest of the dry ingredients, stir to combine.

Add the egg and butter and cut it into the flour mixture with a spatula or pastry scraper to form rough crumbs.

Start to bring the mixture together with your hands to form a dough. Knead the pastry until all the flour is fully absorbed and it becomes a smooth ball. Wrap in plastic wrap and place in the fridge for 1 hour.

Lay the pastry over a tart or pie tin tucking in the sides until it fits evenly. Roll the rolling pin over the tart case to cut the edges (you can also trim the edge with a knife).

Prick the base with a fork then place back in the fridge for 30 minutes.

To blind bake the pastry, add the pastry to a tart pan as directed above then place a piece of scrunched up baking parchment oven the tart/pie case. Top with baking beads or uncooked rice and bake in a preheated oven at 350F/180C for 30 minutes.

Remove from the oven, remove the baking parchment and baking beads and allow to cool.

Warm the milk in a saucepan then set aside (do not let it boil) Chop up the dark chocolate into small pieces and set aside..

Mix the egg yolks and sugar together in a large bowl until combined then add the cornstarch and mix it thoroughly.

Slowly pour the warm milk into the egg mixture whilst whisking constantly to avoid any lumps.

Once incorporated, pour the egg and milk mixture back into the saucepan and heat it on a low heat.

Stir the mixture constantly with a wooden spoon until the mixture is very thick in consistency (about 10 minutes).

Once thickened, turn the heat off and add the chopped chocolate. Stir it in until completely melted and incorporated.