Ramekin
A ramekin is a small ovenproof dish with straight ridged sides, usually ceramic or porcelain, holding between 100 and 250 ml. It is used for individual desserts that are both cooked and served in the same vessel.
The straight vertical sides are functional rather than decorative: a soufflé needs something to climb. A dish that flares outwards will not let a soufflé rise as an even column. For the same reason a ramekin is buttered in strictly vertical strokes and dusted with sugar before filling.
Ceramic heats more slowly than metal and holds heat longer — an advantage for crème brûlée baked in a water bath, a disadvantage wherever fast heat transfer is wanted.
Beyond soufflés and brûlées, ramekins are used for fondants, individual bakes and cocottes, and as containers for weighed-out ingredients during assembly.