Mushrooms aren't just for salad bars or topping burgers anymore. Mushrooms, besides being delicious, offer surprising nutritional benefits, containing copper, potassium, B vitamins, and selenium. Having a package of frozen mushrooms in your freezer means you'll be able to make a yummy side dish whenever the craving strikes.
Place a skillet over medium heat. Heating the pan empty makes fat spread more easily and decreases the likelihood of sticking. If you're using a nonstick skillet, spray with nonstick spray before putting it on the burner; this helps protect the nonstick coating.
Place your butter in the skillet and swirl the skillet to spread the butter over the bottom as it melts. Cook the butter until it stops foaming and smells slightly nutty. Using room-temperature butter helps; it melts faster. The liquids in room temperature butter are also less likely to burn while you wait for the solids in the butter to liquefy.
Add your mushrooms to the melted butter. You do not have to thaw the mushrooms before cooking them; mushrooms naturally contain a lot of water and the little bit added by ice won't make much difference. Use a splatter screen case moisture causes the butter to splatter, which can burn your hands or face.
Cook the mushrooms, stirring frequently, until most of the liquid has evaporated, then add the shallots and cook for a few minutes more. The mushrooms are done when the shallots are translucent, there is no visible moisture and the mushrooms have darkened in color. Don't let them turn black; you're looking for medium-brown. Black mushrooms are burned mushrooms.
Garnish and serve. Transfer the mushrooms to a serving platter and sprinkle the parsley over the top. Serve hot.