Combine the cider, spices, and orange zest in a small pot.
Bring the mixture to a low simmer over medium heat. Let it simmer slowly for 10 minutes. You want it to just barely be simmering, not boiling.
Strain the mixture through a fine-mesh sieve into a heatproof measuring glass.
Divide the strained liquid between two mugs. Top each one with 1 ounce of spiced rum. Serve immediately.
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Notes
Skip the straining--To skip the straining step, bundle the spices and orange zest in a piece of cheesecloth and tie the ends together. Once you're finished simmering the cider, simply grab the cheesecloth pouch and remove it. No straining required.
Keep it hot--If you're enjoying this in the great outdoors, skip the mugs and pour your cocktail into a thermal mug with a lid. This will keep it warm for much longer.
Dietary--This recipe is suitable for gluten-free, dairy-free, and vegan diets.