Turn slow cooker to high and pour in apple cider. Cover and allow it to begin warming.
Heat a small skillet over medium-high heat. Add cinnamon sticks, cloves, cardamom pods, coriander seeds, and star anise. Toast while stirring for 2 to 3 minutes until fragrant and slightly darkened.
Transfer toasted spices into a reusable spice bag or add directly to the cider.
Cover and let cider mull on high for about 4 hours. Reduce heat if bubbling begins to maintain gentle simmering.
Ten minutes before serving, stir in brandy if using.
Taste and adjust sweetness with raw sugar, adding one rounded teaspoon at a time. Add lemon zest if needed for brightness.
Remove spices before extended serving to prevent over-infusion. Serve warm with optional nutmeg garnish.
