This section is from the book "Our Edible Toadstools and Mushrooms and How to Distinguish Them", by W. Hamilton Gibson. Also available from Amazon: Our Edible Toadstools And Mushrooms And How To Distinguish Them.
In all cases the mushroom should be fresh, clear and free from the insect indications mentioned on page 131. Some epicures recommend that the specimens be also washed in cold acidulated water and dried in a cloth; for what reason is not clear, unless the mushrooms are sufficiently dirty to require such cleansing process.
"Take a good quantity of mushrooms, cut off the earthy ends and wash them; stew them, with some butter, pepper, and salt, in a little good stock until tender; take them out and chop them up until quite small; prepare a good stock as for any other soup, and add it to the mushrooms and the liquor they have been stewed in. Boil all together and serve. If white soup be desired, use the white button-mushrooms and a good veal stock, adding a spoonful of cream or a little milk, as the color may require." - W. Smith.
Other mushrooms may be substituted for the ordinary Campestris above mentioned. A very good mock oyster soup may be prepared from the mushrooms Hydnum and the Agaricus ostreatus.
"To make a puree of mushrooms, select such as are of a globular shape, called 'button-mushrooms;' wash them in cold water and wipe them dry; chop them as fine as possible and press them in a cloth; put them in a stewpan with a little butter and pepper; let them stand over a brisk fire, and when the butter is melted squeeze in lemon-juice and add jelly broth, according to the quantity of the mushrooms. Stew until reduced to the consistency of pea-soup, and serve with meat, fish, or poached egg." - Cooke.
Put about two ounces of butter into a stewpan; when thoroughly melted add a teaspoonful of salt, and from a quarter to half the quantity of black pepper, according to taste, and a small bit of mace or a pinch of powdered nutmeg. Having a pint of the mushrooms in readiness, put them in the pan, cover closely, and stew them till they are tender, which will probably require from twenty minutes to half an hour. The addition of flour stirred in cream or milk, by which the stew is thickened, is by some considered a desirable addition. This recipe is given with special reference to the Campestris, but will be found suitable for other mushrooms of the same consistency.
Remove the stems, and place the mushrooms in a double wire broiler over the coals, with the gill sides down, for about two minutes, or even less if the specimens are small. The broiler should then be turned, and the cooking should proceed for two minutes more; towards the end of that time the juicy gills should be sprinkled with salt and pepper, a small piece of butter being finally melted in each as they are served on the hot toast. By this simple method all the natural juices of the mushroom are retained and the true aroma and flavor is conserved. Bacon toasted over the mushrooms is considered by some to improve the flavor.
Take mushrooms of good size, remove the stems and cut their tops in halves or quarters, which, with the chopped stems, should then be immersed in olive oil, spiced with salt, pepper, and a piece of garlic, for about two hours. They should then be put into a stewpan with oil and cooked over a brisk fire. A variation of this method includes the addition of chopped meat and the yolks of two eggs, the whole being slightly browned in the oven before serving.