Preheat oven broiler. In heated 9" skillet, melt butter over medium heat. Add mushroom slices. Sauté until mushrooms are cooked, stirring occasionally. Pour eggs over mushrooms. When eggs are starting to cook around edge of skillet, lift edges with spatula and tilt pan. This creates a fluffy effect. Cook until eggs are just about done. Place cheese slices over eggs in star pattern. Broil for a few moments, until eggs are fully cooked.