Prep the mushrooms: Gently pat the mushrooms with a clean towel to absorb any excess moisture. Trim off the hard stem at the base of each clump of mushrooms. Separate large clusters into more bite-sized pieces, using your hands or a knife.
Place a large (10-12-inch) nonstick pan over medium-high heat. When a drop of water sizzles and evaporates on contact, add the oil to the pan. Arrange the mushrooms in one layer. Cook, without turning, until one side is golden brown and crisp. Sprinkle with salt and pepper to taste and toss. *Note: If the mushrooms don't fit in one layer in your pan, cook them in 2 batches, adding a little more oil as needed.
Transfer the mushrooms to a serving platter. Without returning the pan to the heat, add the butter, garlic and parsley to the hot pan, swirling until the butter melts and the garlic is fragrant.
Pour the garlic butter over the mushrooms and serve.
Ideas for serving:
Make mushroom toast: Spoon over toasted slices of garlic bread with some grated Parmesan cheese or melted cheese.
Toss the mushrooms with cooked pasta.
Add the mushrooms to softly scrambled eggs for a fancy breakfast dish.