Preheat oven to 375°. Place milk in a small bowl; set aside. Place flour in a small bowl; set aside. Place egg in a small bowl; set aside. Combine breadcrumbs and salt in a medium bowl; set aside. Submerge each mushroom in milk; shake off excess liquid and dredge in flour. Submerge in beaten egg; dredge in breadcrumbs. Place on baking sheet; repeat with remaining mushrooms. Bake 15 to 20 minutes, until golden brown and lightly crisped. Serve warm.