Mix the cheese base In a medium bowl, mash the Boursin cheese until smooth. If using, fold in the finely shredded cheddar and a pinch of black pepper.
Chill briefly Scoop the mixture onto plastic wrap, shape into a ball, and refrigerate for 20–30 minutes until slightly firm but still spreadable.
Prepare the coating On a plate, gently combine the chopped pecans and minced chives. Keep pomegranate arils separate for best texture.
Coat the cheese ball Roll the chilled cheese ball in the pecan mixture first, pressing gently so it adheres. Then press the pomegranate arils mostly on the top and sides for a clean, polished look.
Finish and serve Sprinkle lightly with flaky salt if desired. Transfer to a serving board and add crackers or crostini.