Preheat oven to 400°. In a large skillet, cook sausage, onion and garlic over medium heat, breaking up sausage into crumbles, until meat is no longer pink and onion is tender, 6-8 minutes; drain. Add cream cheese and Parmesan cheese; cook and stir until melted. Stir in bread crumbs, basil and parsley., Meanwhile, place mushroom caps in a greased 15x10x1-in. baking pan, bottom side up. Brush with melted butter. Spoon sausage mixture into mushroom caps. Bake, uncovered, until mushrooms are tender, 12-15 minutes.