Stir cream cheese, Cheddar, pear, scallion white, salt, and pepper together in a medium bowl.
Coat a large piece of plastic wrap with cooking spray. Scoop the cheese mixture onto it. Using the plastic wrap to help you, form the cheese mixture into a ball, then completely wrap in plastic. Refrigerate for at least 1 hour and up to 2 days.
Just before serving, combine pecans and the reserved scallion greens in a shallow dish. Roll the cheese ball in the mixture, pressing to adhere.
