Use a vegetable peeler to peel the zest from one of the oranges, and then slice the second orange into thin slices.
Place the cider in a large pot. Squeeze the juice of the peeled orange into the pot, and add the strips of orange zest, cloves, cinnamon sticks, and allspice berries. Bring to a simmer over medium-high heat, and then reduce the heat and simmer for 15 to 30 minutes, stirring occasionally. The longer it simmers, the more concentrated the flavors will get.
Strain the cider through a fine-mesh strainer. Pour the mulled cider into mugs and garnish with a slice or orange. Serve hot
Notes
If you choose to use mulling spices instead of the above ingredients, use about 2 tablespoons for 2 quarts (½ gallon) of apple cider. If your mulling spice blend has orange or other citrus in it, you can skip the orange juice and peel in the cider. Or still, add it for a nice burst of citrusy sweet-tartness.
Apple cider is perishable and must be refrigerated. As cider ages in the fridge, it starts to ferment and can even turn “hard” over time, meaning that it starts to develop alcohol content.
Apple juice, left sealed, can stay at room temperature for months without spoiling. Check the sell-by date to be sure, and refrigerate it once it’s been opened.