Mushrooms a la Soyer

From 1912:

Toast a square slice of bread to a delicate brown; lay it on a dish and put on it four freshly gathered mushrooms. The toast should be spread with Devonshire cream and the mushrooms should be filled with it; or, if this is not at hand, ordinary cream or butter may be used in place of it. A little salt and white pepper are to be dredged over the mushrooms. Next put a common tumbler over each mushroom, leaving a little space between, and set the dish before the fire, turning it about continually, that the glasses may not break. In about 20 minutes the mushrooms should be done, the glasses will be filled with vapor, and one minute should elapse after removal from the fire before they are taken off the bread. This dish is attributed to M. Soyer, who is said to have invented it while visiting Devonshire.