Preheat the grill to medium high.
Separate the mushrooms from the stems.
With a mushroom brush or a damp towel, clean the top surface of the mushrooms.
Brush or spray the mushrooms with extra virgin olive oil.
Arrange the mushrooms on the grill rack and grill for 3 - 5 minutes.
Flip the mushrooms and cook for an additional 2 - 4 minutes, depending on the thickness of rat mushrooms.
Remove to a plater, season with salt and freshly ground pepper.
Sprinkle the parsley on top and serve immediately.