Add all the ingredients to a large pot, including 1/2 the orange after it is squeezed. Simmer on low until desired temperature is reached. I keep mine on low all day or evening so that the house smells wonderful. You can also warm it in a crockpot, if you need stove space during the holidays. I save my apple cider container and pour the spiced cider back into the container if I have any left over. Serving size is a rough guess. It really depends on the size of your mugs.