Add apple cider to the slow cooker. You’ll need to add the fruit to it, so if you cannot fit the whole gallon, don’t worry about it.
Add the fruit to the cider. Add the cinnamon sticks. Stir in the brown sugar.
Heat, covered, on high for 2 hours. Add the light sprinkle of spices. Cover again, turn down to low and heat for one more hour. At this point, it’s ready to serve.
You can add in more cider as the mulled cider in the slow cooker begins to disappear. Just stir it in, and the spices will combine with the newly poured cider.