Preheat oven to 375 degrees. Grease a 9" by 13" casserole dish. Sprinkle with fried onions. Layer with thinly sliced sweet potatoes, then bacon, then green onions, then Gruyère and finally cheese mix. Whisk 8 eggs and the cream together. Stir in the spices. Pour over the sweet potato bacon mixture.
Bake at 375 degrees for 30 to 40 minutes, until set. Serves 8. Can be made the night before and baked in the oven the next morning.