Crème Pâtissière (Pastry Cream)

Split the vanilla bean lengthwise, scrape out the seeds, and add both pod and seeds to the milk in a medium saucepan. Heat over medium heat, stirring occasionally, until the milk just reaches a simmer — small bubbles at the edges, steam rising. Remove from heat, cover, and steep for 10 minutes to deepen the vanilla infusion. Remove the pod (rinse and dry it for vanilla sugar).

In a large bowl, whisk the egg yolks and sugar together vigorously for 1–2 minutes until the mixture is pale, thick, and forms a ribbon. Sift in the cornflour and whisk again until completely smooth with no lumps. This paste must be completely lump-free or the finished cream will have starchy pockets.

Pour a ladleful of the hot infused milk into the egg yolk paste, whisking constantly and vigorously to raise the temperature of the yolks gently without scrambling them. Once combined, pour in the remaining hot milk in a slow, steady stream while whisking. Return the entire mixture to the saucepan.

Return the custard to the saucepan and cook over medium heat, whisking constantly and reaching into every corner of the pan. The mixture will first appear to thicken slightly, then will suddenly seize up and become very thick — keep whisking as it crosses from liquid to thick paste. This is the starch gelatinising. Crucially, once the cream has thickened, continue cooking at a full boil for 1–2 minutes, whisking hard, to cook out the raw starch flavour. Remove from heat, beat in the cold butter, and press cling film directly onto the surface. Refrigerate until cold and firm (at least 1.5 hours).