Put 600 ml of Whole Milk into a saucepan and add a halved Onion studded with 4–6 Cloves, 1–2 Bay Leaves and a teaspoon of whole Black Peppercorns. Warm gently to just below a simmer, then reduce heat and let the milk poach very softly for 15–20 minutes so it picks up the aromatics.
While the milk infuses, melt 25 g of Unsalted Butter in a small frying pan and add 120 g of White Breadcrumbs. Toast the crumbs over medium heat, stirring, until they are pale golden and fragrant — about 3–5 minutes — then remove from the heat.
Strain the infused milk through a fine sieve into a clean saucepan, pressing on the onion solids to extract flavor, then discard the solids. Return the strained milk to a low heat and stir in the toasted breadcrumbs.
Add 60 ml of Double Cream and another tablespoon of Unsalted Butter to enrich the sauce. Stir continuously until the mixture comes together and thickens to a spoon-coating consistency, 4–6 minutes.
Season with a generous pinch of Ground Nutmeg, salt to taste (Salt) and a little freshly ground White Pepper. Taste and adjust seasoning and consistency — if it’s too thick, loosen with a splash more milk or cream; if too thin, cook a little longer.
Turn off the heat and let the sauce rest for a few minutes so the flavors mellow. Serve warm alongside roast poultry or spooned over slices of meat.
