Preheat oven to 350 degrees. Spray a 2-quart casserole dish with non-stick spray. In a large bowl, whisk eggs and milk. Stir in cheese, mushrooms and sliced olives. Pour mixture into casserole dish. Bake 40-45 minutes until knife inserted in the center comes out clean. Let cool about 10 minutes, then cut into slices and serve. Makes 6 servings.