This section is from the "The New Home Cook Book" book, by Ladies Of Chicago Et Al. Also available from Amazon: The Home Cook Book: Tried, Tested, Proved.
The casserole is a simple covered dish made of fireproof pottery. It is counted as among the very newest and most aesthetic of developments among cooking and table wares. But it is not a new thing under the sun for this same sort of a dish, in its coarser forms and with a heavy, coarse, round handle which was continuous with it, was used generations ago by the French peasants whose custom it was to imbed it in the ashes at night so as to have their breakfast all ready for them in the morning. The cooking principle of the dish is the same as that of the fireless cooker - long and slow cooking.
It is possible to-day to buy the coarse, rather homely — so homely as to be pretty, some one has said — heavy-handled thing such as the very poor French people used. From the low price paid for these one may go all the way up through a range of prices to those costing many dollars. The great cost of the most expensive is in their table frames, which are often very finely finished and made of silver, copper, or platinum. The earthenware for these is beautifully enamelled and colored, but the food cooked in the coarser ware, everything else being equal, has the finer flavor.
These dishes vary in shape and size and are round, oval, oblong, high, and low. They are mostly of family size but some of them are for individuals. They are especially recommended as being not only attractive but sanitary and durable, and possessed of the old-fashioned usefulness. For informal table service the quite common casserole of brown cooking ware, with other things to match, is taken directly from oven to table; usually with a napkin around it to keep in the heat as well as for appearance's sake. In this way not a bit of the flavor of the vegetable or meat is lost.
The name of this utensil is French, and the term "en casserole" is used to describe the sort of cooking for which it is used. As the fowl was the great meat of the French it is natural that in cooking this, both in their soup pot, which was of earthenware with a cover, and in their casserole, they should attain perfection. All kinds of fowl and game are among the most delicious things that can be prepared in this way, but there are many delicious combinations of meat and vegetables, meat and macaroni or rice so prepared. Vegetables cooked en casserole may be made very savory.