Chocolate pistachio gateau basque

Pulse the flour, sugar, a pinch of salt, a little baking powder and the cocoa powder together.

Add the softened butter, then the eggs, and process until the dough comes together.

Pipe about half the chocolate dough over the bottom of the greased pan; pipe a last rope along the rim, smooth it with the back of a teaspoon and scrape away the excess for a clean border.

Heat the milk with a third of the sugar; mix the egg yolks with the remaining sugar, then the flour and cornstarch.

When the milk boils, temper the yolks with it, return everything to the saucepan over medium heat and whisk continuously until it thickens and boils.

Cook 2 more minutes, then stir in the pistachio paste.

To cool quickly, spread the cream over a frozen tray lined with plastic wrap, cover with another and refrigerate until completely chilled.

Smooth out the chilled pastry cream and spread it in the dough-lined pan.

Roll the remaining chilled chocolate dough into a thick disc, close the cake, seal and remove the excess dough.

Prick, brush with egg white only, mark a criss-cross, and bake in a fan oven at 330F / 160C for 40 minutes.