A soufflé is an egg-based dish that holds its "puffed" structure by the presence of hot trapped air. Soufflés are temperamental and deflate rather quickly once taken from the oven. Soufflés can be made either savoury or sweet, served individually or as a whole dish. Traditionally they are served in soufflé ramekins, which are flat-bottomed porcelain cups similar in appearance to crème brûlée cups. When a soufflé ramekin is not available, virtually any ceramic dish can be used.
Mugs and Tea Cups
Medium to short mugs and tea cups work great for individual servings of sweet or savoury soufflés. They can be greased, baked in the oven as long as the ceramic is heat-resistant, and they have the added advantage of having a handle to hold. Tall coffee mugs can be used; however, they require the soufflé to rise much higher than usual to "peak" out of the cup.
Crème Brûlée Ramekins
Crème brûlée ramekins, or cups, are virtually the exact same as soufflé dishes, just slightly shorter. These work if you are making small ppetizer soufflés, as they hold much less volume than full-size individual soufflé dishes. The cups can be prepared and used exactly the same way as soufflé dishes, granted they are heat-proof.
Ceramic Casserole Dish
The best replacement for a large soufflé dish is a large ceramic casserole dish, either rectangular or circular. Virtually any ceramic dish that is heat-resistant with tall sides can be used. Circular casseroles are the best option.