Pour the wine and brandy into your saucepan, then add the orange slices, cloves, cinnamon sticks, star anise, and two tablespoons of your chosen sweetener. Give everything a quick stir so the spices are evenly distributed through the liquid. I like to do this step first so the spices have more time to mingle with the wine while it heats.
Place the pot over medium-high heat and let it warm until it is just about to simmer, but never let it actually boil. Boiling wine burns off the alcohol and can make the flavor taste flat, so I always keep a close eye on it during this stage. Once you see the first tiny bubbles forming, turn the heat down right away.
Reduce the heat to low, cover the pot, and let the wine simmer gently for at least 15 minutes. I often let mine go for closer to 45 minutes to an hour because the flavor only gets better the longer it sits. If you have the time, a longer simmer is always worth it.
Once the wine smells fragrant and spiced, use a fine mesh strainer to remove the orange slices, cloves, cinnamon sticks, and star anise. Give it a taste at this point, and stir in a little extra sweetener if it needs it. I usually end up adding one more tablespoon of honey here because my taste runs a bit sweet.
Ladle the strained mulled wine straight into heatproof mugs while it is still warm. I like to drop in a fresh cinnamon stick or a slice of orange on top for a nice festive touch. Serve it right away so everyone gets to enjoy it piping hot.