Add wine, brandy, orange slices, cloves, cinnamon, star anise, and 2 tablespoons sweetener to a large saucepan. Stir briefly to combine.
Cook the mulled wine on medium-high heat until it just barely reaches a simmer. (Avoid letting it bubble — you don’t want to boil off the alcohol.) Reduce heat to low, cover, and let the wine simmer for at least 15 minutes or up to 3 hours.
Using a fine mesh strainer, remove and discard the orange slices, cloves, cinnamon sticks, and star anise. Give the mulled wine a taste, and stir in extra sweetener if needed.
Serve warm in heatproof mugs, topped with your favorite garnishes.
