Terracotta cazuelas are vessels used for cooking and serving and traditionally come from Spain. The come in various sixes and the deeper ones will usually have a lid. They are unglazed on the outside and not only look charming but cook evenly and hold the heat as well. Smaller ones tend to be used for the tapas and the large, shallow ones for main meals. The large deep ones are used for cooking only but can of course, be taken to the table to serve, in the same manner as a casserole.
When cazuelas are new, they need to be seasoned. The easiest way, is to soak them in cold water for 12 hours. Drain and dry them, then rub some cut garlic over the unglazed parts. Brush them all over, including the bottom, with groundnut oil (olive oil is too high in mono-unsaturated fats for this purpose) and put them into a cold oven. Turn on the heat to 150°C / 300°F / Gas 2 and leave for 1 hour and 30 minutes. Allow to cool and wash in warm soapy water.
Once seasoned, cazuelas in general, can be used in the oven and on the hob but do read the manufacturer's instructions as some can only be heated in the oven.