Pour the apple cider into your large pot or Dutch oven, then add the cinnamon sticks, star anise, cloves, and orange slices. Give everything a gentle stir so the spices are evenly distributed through the liquid. Place the pot over medium heat on the stove.
Let the mixture heat up until it reaches a gentle simmer, watching so it doesn't come to a full rolling boil. Once it's simmering, reduce the heat to medium-low so the spices can infuse slowly. This slow approach is what gives the cider its deep, cozy flavor.
Keep the pot partially covered and let it simmer for about 15 to 20 minutes. This is the stage where the cinnamon, star anise, and cloves really do their job, turning plain apple cider into something warm and fragrant. Taste it partway through and stir in a little sugar if you'd like it sweeter.
If you're serving right away, ladle the hot cider carefully into mugs, avoiding the loose cloves as best you can. If you're making it ahead, let the pot cool completely first, then strain out the spices before storing. Either way, garnish each mug with a fresh cinnamon stick or star anise pod for a festive touch.