Jelly
Jelly, in raised pie making, is a gelatine-rich savoury stock poured into the baked pie through a hole in the lid, where it sets as the pie cools and fills the gap left by the shrinking filling.
The filling of a raised pie contracts as it cooks, leaving an air gap under the crust where the meat would dry out and spoil faster. Warm jellied stock, made by simmering bones and trotters or fortified with leaf gelatine, is funnelled in while liquid and sets solid once the pie is chilled.
Season the stock well, because chilling dulls flavour, and pour it in stages so it can find its way around the filling. A pork pie is the classic example, but a cold chicken and ham raised pie is finished the same way.