Definition of quaking custard in English:

quaking custard

noun

  • A type of custard (typically sweet) having a slightly loose or wobbling texture when set; (later) specifically (US) a custard-based dessert thickened with both gelatin and beaten egg white, causing it to separate into two layers, one smooth and one fluffy.

Origin

Early 17th century; earliest use found in Ben Jonson (?1573–1637), poet and playwright.