In A Large Bowl, Beat Cream Cheese And Mayonnaise Until Smooth. Beat In The Artichokes, Parmesan Cheese And Onion. Lightly Spray Tops Of Mushrooms With Cooking Spray. Spoon Cheese Mixture Into Mushroom Caps. Combine Bread Crumbs And Oil; Sprinkle Over Mushrooms. Grill, Covered, Over Indirect Medium Heat For 8-10 Minutes Or Until Mushrooms Are Tender.