Sauté onions and mushrooms in butter for 5 minutes.
Blend in flour, salt, pepper and nutmeg. Gradually add cream, stirring to boiling point. Taste for seasoning. In buttered casserole, spread half the spinach; cover with half of the mushroom sauce, then repeat. Sprinkle with the grated cheese. Set in pan of hot water. Bake at 325F for 40 minutes.
269 calories, 23 grams fat, 12 grams carbohydrates, 7 grams proteinper serving. This recipe is low in carbs.