Combine 2 cups of chicken stock, 1/4 teaspoon salt, 1 teaspoon coarsely ground black pepper and the thyme sprig in a large skillet or sauté pan. Bring to a boil then add the chicken breasts making sure they fit in a single layer. Reduce the heat to simmer and cook for 30 minutes, turning at least once. Turn off the heat and cover the pan. Allow the chicken to rest in the hot broth and finish cooking for about 15 more minutes. Remove the chicken and cut into bite sized pieces or shred, set aside. Remove the thyme sprigs but keep the chicken stock handy.
While the chicken is cooking combine all the dry spices in a small bowl. Set aside.
Once the chicken is shredded, heat the oil in a large soup pot over medium-high. Add the onion and sauté until it starts to soften. Add the garlic, ginger, and chicken. Sauté for 1 minute to combine. Add all the spices to the chicken mixture and stir until the chicken has taken up all the spices.
Pour the reserved and remaining 3 cups of chicken stock, coconut milk and passata into the soup pot. Reduce the heat to medium-low and cover the pot. Gently simmer the soup for 30 minutes stirring occasionally.
Add the lentils, cover the pot and continue to cook gently on low for another 15 minutes or until the lentils are cooked.
Remove from the heat and check the seasoning. And add salt and pepper to taste. Add the fresh lemon juice and the spinach leaves. Stir until the spinach is just wilted.
Serve immediately garnished with parsley and chopped cashews.