Place diced onion in a skillet cook for about 5 minutes.

Add the chicken breasts with salt and pepper and cook for about 10 minutes in both sizes.

Pour the broth.

Cook for about 20 minutes or till the breasts are well done.

Combine basil, spinach, walnuts, olive oil, garlic, lemon juice, and tamari in a food processor. Pulse well until smooth.

Transfer to a jar and store in the fridge until the chicken is ready.

Remove chicken from the skillet and shred with two forks.

Mix in the pesto and toss well.