Prepare a baking sheet or casserole dish with cooking spray. Set aside. Preheat oven to 425℉ or the barbecue grill to medium heat.
Clean mushrooms and cut into quarters or slices. Season with Lemon Pepper Paradise (or your favorite lemon pepper) and Peppercorn Perfection (or salt and pepper) and toss with olive oil. Spread mushrooms out onto prepared dish.
Roast or grill for approximately 15-20 minutes in the oven, or 10 minutes on the grill, until mushrooms, but still juicy. Remove from heat.
Place the mushrooms in a serving dish, coated with cooking spray or olive oil.
Blanket the mushrooms with thin slices of Gruyere cheese and return to the oven or the grill for the final 5-10 minutes, or until the cheese is melted, and gooey, but not too browned.
Garnish with a sprig of parsley and serve hot!