A shirred egg is one that is broken into a small, flat, buttered dish and cooked quickly under the broiler. The white is softly set and tender, and the yolk is liquid, but covered by a shimmering, translucent film. Shirred eggs should never be attempted in the oven, as it toughens them.
Place the dish over moderate heat and add the butter. As soon as it has melted, break the egg or eggs into the dish and cook for about 30 seconds until a thin layer of white has set in the bottom of the dish. Remove from heat, tilt dish, and baste the egg with the butter. Set aside.
A minute or so before serving, place the dish an inch under the hot broiler. Slide it in and out every few seconds and baste the egg with the butter. In about a minute the white will be set, and the yolk filmed and glistening. Remove, season, and serve immediately.