Puff pastry
Puff pastry is a fully laminated dough of hundreds of alternating butter and dough layers that bakes into a tall, shattering, flaky crust.
Made from scratch it is a project of repeated folds and long chills. Bought all-butter puff is one of the most defensible shortcuts in cooking, and the standard lid for a quick pot pie.
Puff needs a hot oven, at least 200C (400F), to generate the steam that lifts it before the butter melts out.