Coat a lg grill pan with a non stick cooking spray. Place over med heat. Add chicken and cook 5-6 mins per side or until it reaches 165 degrees inside. Remove from heat, slice into strips and set aside.
In a lg bowl combine spinach, apple slices, nuts and vinaigrette, toss to coat. Place salad on 4 plates, season with salt and pepper to taste.
Top each salad evenly with sliced chicken and 1 Tbsp of the crumbled cheese. Drizzle with more dressing if you wish and serve at once.