Step 1

Trim and halve (or quarter if large) 1 pound fresh mushrooms. Add half the mushrooms to a food processor fitted with the blade attachment. Pulse until finely chopped, scraping down the sides of the bowl occasionally, 7 to 8 (1-second) pulses. Transfer to a medium bowl. Add the remaining mushrooms to the food processor, pulse until finely chopped, and transfer to the bowl. (Alternatively, very finely chop everything by hand.)

Step 2

Finely chop 2 small shallots (about 1/4 cup). Mince 1 garlic clove. Pick the leaves from 5 to 6 fresh parsley sprigs until you have 1 tablespoon and finely chop.

Step 3

Melt 4 tablespoons unsalted butter in a large skillet over medium heat. Add the shallots and garlic and cook, stirring occasionally until softened, 2 to 3 minutes. Add the mushrooms, 1/2 teaspoon kosher salt, and a few grinds of freshly ground black pepper. Cook, stirring occasionally, until the mushrooms are softened and have released their liquid, 4 to 5 minutes.

Step 4

Increase the heat to medium-high and cook, stirring occasionally, until the liquid is evaporated and the mushrooms begin to stick to the bottom of the pan, 2 to 3 minutes. Remove from the heat and stir in the parsley.