In France, the term cooking “à la Florentine” refers to anything cooked with spinach and Mornay sauce. Chicken, fish or vegetables . . . almost anything will work well on a bed of sautéed spinach, doused in a homemade Mornay sauce and melted cheese. Broiled under the grill and served with toasted bread, this luscious, creamy egg dish will delight any spinach lover.