Combine apple juice, cinnamon sticks, cloves, allspice, orange peel, orange juice and lemon peel into the slow cooker.
Set the slow cooker on high for 3 hours or low for 8-10 hours, covered.
Strain the spices out of the mulled apple cider. Taste the drink and adjust sweetness to taste with brown sugar if desired.
Serve hot, and add a splash of rum or bourbon if desired to spike the drink.
Notes
This recipe can simmer on the stovetop in a large saucepot for 40-60 minutes if you prefer it to the slow cooker. A lengthier cooking time allows for more spice to infuse, so taste and adjust accordingly.
Recipe by Uproot Kitchen at https://uprootkitchen.com/2017/11/20/slow-cooker-mulled-apple-cider/