Season chicken, if desired, with salt and ground black pepper. Heat oil in large skillet over medium-high heat and cook chicken, turning once, 12 minutes or until chicken is thoroughly cooked. Remove chicken and cool.
Combine spinach, onion and Wish-Bone® Chunky Blue Cheese Dressing in large bowl. Evenly divide spinach salad on serving plates, then top with sliced chicken and garnish with apple and pecans. Serve, if desired, with additional Dressing.