Melt butter in a large skillet over medium heat. Add Garlic Butter Seasoning and stir. Add mushrooms, cap side down, in a single layer. Cook undisturbed until brown on the bottom, about 5-7 minutes. Turn over all mushrooms and cook undisturbed until browned on the second side and tender, about 5-7 minutes more. Sprinkle with fresh herbs, if using, and serve.
Note: To cook mushrooms in an even layer, trim down stems to be even with each mushroom cap, or remove stems and reserve for another use.