A ham-and-cheese croissant–quiche hybrid bakes croissant pieces with smoked ham, cheese, and a mustardy savory custard, perfect for using stale croissants.
How Much Butter Is In A Single Croissant? - Tasting Table
A typical croissant contains roughly 25–30% butter by weight, often a couple of tablespoons, and benefits from high-butterfat European butter for best flakiness.