Chiffon pie

The base, often a cooked mix of egg yolks, sugar and fruit juice such as lemon, lime or pumpkin, is thickened with gelatin and cooled until it begins to set. Beaten whites or whipped cream are then folded in, and the mousse-like filling is piled into a blind-baked or crumb crust and chilled until firm.

Timing matters: if the base is too warm the foam deflates, and if it has fully set it turns lumpy. Many modern recipes use a cooked meringue instead of raw whites.