Preheat oven 350°F
Cook chicken (if not using deli or leftovers)
Toast walnuts until golden brown, approximately 8 minutes
Prep: chop walnuts. Slice bacon. Bite size pieces of chicken. Finely chop onion. Chop apple
cook bacon until crisp. Drain and crumble
Whisk vinegar, mustard, salt, and pepper. Whisk in oil
Combine 2T dressing with chicken and let sit 5 minutes.
Add walnuts, bacon, spinach, onion, apple, and remaining dressing. Toss