Pour 1 gallon of apple cider into a 5-quart or larger slow cooker

Cut 1 medium orange into 1/4 inch thick rounds. Cut 1 1/2 inches of ginger crosswise into 1/4 inch thick slices. Add both to the slow cooker

Add 5 (3-inch) cinnamon sticks, 1 tablespoon whole cloves, and optional spices (like star anise). (To make it easier to serve, place the cloves and spices in a tea ball first, or place in a double layer of cheesecloth or paper coffee filter, gather it into a sachet, and tie it closed with kitchen twine.)

Cover the slow cooker and cook until the flavors meld, 4 hours on LOW. (If there are clumps of spices floating at the top you wish to remove, strain cider through a fine-mesh strainer or cheesecloth into a large pot.) Keep warm and serve in mugs garnished with more orange slices if desired.