The white mushroom is known in French as champignon de Paris because as early as the 17th century it was cultivated by Louis XIV’s gardeners in vaults under the city of Paris. It is relatively small (hence its other name, “button” mushroom) with a thick, short and uniform stem. White or coffee-colored (the latter being more flavorful), it’s a mushroom that lends itself to countless uses: as good on a pizza as in the duxelles for Beef Wellington. 

Buying
The cap should be firm and unblemished with no signs of softness, and firmly attached to the stem.
While the color of the cap depends on the particular variety, the color of the gills, which darken with time, should be as light as possible. Ideally the cap should be so tightly closed that the gills are not visible.

Storing
Mushrooms are delicate, but will keep several days in the refrigerator in a plastic bag supplied with air holes. When uncovered they dry out rapidly.
To keep longer, cover with olive oil. Mushrooms cannot be frozen.

When dried they retain all their flavor. Place them on a baking sheet at room temperature or in a very low oven. Once dry, they can be pulverized and used to flavor many different dishes or rehydrated in cooking liquid.

Preparing
Mushrooms must not be washed! Simply scrape them with the point of a knife or brush them. The caps can also be wiped with a damp cloth.                   
Never soak them in water since they absorb liquid like a sponge.     
Cut off the end of the stem. There is no need to peel the mushrooms before cooking.

Cooking
They can be eaten raw in salads, simply sliced and drizzled with a little lemon juice to prevent them from darkening.

Don’t forget to draw out their water before cooking – otherwise you’ll end up with “boiled” mushrooms which are much less tasty and which have an unpleasant texture.

Hint: adding a handful of stale bread to the skillet when cooking mushrooms will absorb their cooking juices. Then they can be grilled much more quickly. Add a touch of parsley and garlic.

Enjoying
Firm mushroom caps are perfect for the grill. Thread some onto skewers with small bay leaves and pieces of Toulouse-style sausage (pork garlic sausage).

Duxelles
Duxelles is a finely chopped mixture of mushrooms and shallots sautéed in butter. Gently cook the shallots in butter without letting them color; add the mushrooms and cook over low heat, covered, until the water from the mushrooms has evaporated. It is a basic preparation used in stuffings and sauces. If the duxelles is to be used as a garnish, add 1 tablespoon fresh cream. You could also add a little parsley, garlic butter, etc., to taste.