Place the chicken, carrots, onion, celery, parsley, Herbes de Provence, paprika, chili flakes, chicken bouillon, garlic, chicken stock, salt, and pepper in a 6-quart slow cooker.
Gently stir to combine. Cover and cook on high for 4 hours or on low for 7 hours.
Uncover and shred the chicken. I just do this in the slow cooker with two forks, or you can remove to a cutting board if that’s easier. Then add the chicken back in.
Whisk the cornstarch and milk together. Pour into the soup. Add the gnocchi and spinach, place the lid back on, and cook for another 30-60 minutes on high. The soup should thicken and become creamy, keep stirring it and it should thicken. Add a little more cornstarch slurry if not thickening enough for your preference.
Remove some broth and mix it with the yogurt. Add it back to the soup, taste and adjust seasonings; add more salt and pepper as desired.
Ladle into bowls, and add garnishes, and serve with warm, crusty bread.
