Pastry cream

Heat the milk with half of the sugar.

Meanwhile gently beat the egg yolks with the remaining sugar, the vanilla, the flour and the cornstarch.

Temper the yolk mixture with half of the hot milk, mix well and return it to the saucepan.

Bring to a boil and cook for two minutes, whisking constantly, for a smooth lump-free custard; if it goes lumpy, fix it with an immersion blender.

Off the cooking, add butter or mascarpone and blend.

Spread onto a frozen tray lined with plastic wrap so it cools faster, cover with another sheet of plastic film and refrigerate.

Right before using, beat the chilled pastry cream on high speed.