Heat the broiler. In a 12-inch nonstick skillet, heat the butter and olive oil over medium-high heat. Add the mushrooms; cook for 3 to 4 minutes or until tender, stirring frequently.
Stir in the green onions, rosemary, sage, salt and pepper; cook 30 seconds. Reduce the heat to low.
Meanwhile, in a large bowl, beat the eggs and sour cream with wire whisk until blended. Pour over the mushroom mixture and cover pan. Cook for 5 minutes or until almost set.
When the eggs are nearly set, place the uncovered pan under the broiler with the food about 3 inches from the heat. Broil for 3 to 5 minutes or until golden brown and the eggs are completely set.
Sprinkle with the shredded cheese and cut in wedges to serve.