Spray 9 x 13-inch baking pan with vegetable pan spray. In large saucepan, combine chicken stock, milk, salt, pepper, garlic powder, and nutmeg; bring to a boil. Stir in pureed sweet potatoes; bring back to boil. While constantly whisking, add cornmeal in a slow, steady stream, making sure there are no lumps. If desired, add orange-colored icing. Reduce heat and continue stirring until thick, about 3 minutes. Stir in cream cheese; stir until melted and smooth. Pour into prepared baking pan. Let set at room temperature at least one hour or refrigerate for longer. Cut into shapes with Halloween mini-cookie cutters. Serve. Makes about 4 dozen treats