Wash the mushrooms, remove the stems and drain on a paper towel. Fry the bacon until crisp and drain it. When cool, crumble the cooked bacon into small pieces. Mix bacon together with cheese and green onions. Brush mushrooms lightly with olive oil. Place 2-3 teaspoons of bacon mixture in the hollow of each mushroom. Place on broiler pan. Preheat oven to broil. Place stuffed mushrooms under hot broiler and broil 2-3 minutes or until the cheese bubbles. Serve immediately.
Note: May be stuffed and refrigerated for several hours before broiling.