Prepare outdoor grill for direct grilling over medium-high heat. In small bowl, stir oil, poultry seasoning, salt, black pepper and cayenne pepper. Pat chicken dry with paper towel; rub with oil mixture.
In blender, purée garlic, blueberries, red onion, stock, fruit spread, ketchup and vinegar. Makes about 1 ½ cups.
In small bowl, reserve 1 cup of the blueberry mixture. Place chicken on hot grill rack; cover and cook 20 minutes or until internal temperature reaches 165°, turning frequently. During last 5 minutes of cooking, brush both sides of chicken with remaining ½ cup blueberry mixture. Transfer to serving platter; serve with 1 cup reserved blueberry mixture and garnish chicken with green onion, if desired.
For a little extra kick, use chili sauce instead of ketchup.