Preheat oven to 375°F. Remove the stems from mushrooms; reserve the stems. Season mushroom caps with salt. Mince stems to yield ½ cup; discard remaining stems.
Combine ground beef, minced stems, blue cheese, breadcrumbs, green onions, and steak seasoning. Spoon beef mixture evenly into mushrooms.
Place stuffed mushrooms on a rack in a broiler pan. Bake 15 to 20 minutes. If desired, sprinkle with chives. Makes 40 servings. Recipe from Beef Loving Texans.