Pastry cream is a cooked custard thickened with starch — the foundational cream of French pastry, used to fill éclairs, mille-feuille, fruit tarts, and choux preparations. Its distinguishing characteristic from crème anglaise (unthickened custard) is that it must be brought to a full boil after the starch is added — the starch must gelatinise completely to produce a stable cream that holds its shape and does not weep liquid.
- **The boil is mandatory.** Raw starch tastes of raw flour. Partially cooked starch produces a cream that weeps liquid within hours. The cream must be brought to a full, rolling boil, held for 60 seconds while whisking constantly, to fully gelatinise the starch and eliminate the raw flavour. - **Tempering the yolks.** The hot milk is added to the yolk-sugar-starch mixture gradually — starting with a small amount to raise the temperature, then more. Adding hot milk too fast to cold yolks produces scrambled egg. - **Vanilla infusion.** Vanilla bean split and steeped in hot milk for 15 minutes before making the cream produces a depth of flavour that extract cannot replicate. - **Cover immediately.** Press plastic wrap directly against the surface of the hot cream to prevent a skin from forming. Decisive moment: The first bubble of a full boil — not a simmer — breaking the surface of the cream after the starch has been added. This is the trigger for the 60-second final cook.
Jacques Pépin's Complete Techniques