Place the chicken, carrots, celery, onion, parsley, garlic, Italian seasoning, 1/2 teaspoon table salt, and 1/4 teaspoon black pepper in a large slow cooker.
Add the Better than Bouillon paste and red pepper flakes, if using. (If you are not using Better than Bouillon, you will most likely want to add extra salt to the soup - probably around 1/4 to 1/2 teaspoon on top of the 1/2 teaspoon already in there - but you can always do this to taste at the end to be safe.)
Pour chicken stock or broth on top and give everything a gentle stir to combine. Cover and cook on low for 6-8 hours or on high for 4 hours.
While keeping the slow cooker turned on, take the lid off and shred the chicken using two forks to gently pull pieces apart. (If you find it easier, you can take the chicken out and do this on a cutting board or in your stand mixer, then return it to the pot.)
In a small bowl or liquid measuring cup, whisk together the cream (or half and half) and 1 Tablespoon of cornstarch. Pour this mixture into the soup, then add the gnocchi and spinach and stir well. Put the lid back on the slow cooker and be sure it is turned to the high setting. Let cook for another 30-45 minutes.
Uncover the pot and give the soup a good stir. If you would like it to be thicker, whisk together up to 1 more Tablespoon cornstarch plus an equal amount of cool water, then stir this extra slurry into the soup. It should thicken more over the next 5 minutes or so.
Taste and season with additional salt and pepper, as desired. (You will probably want to add extra salt if you only added 1/2 teaspoon earlier and did not use Better than Bouillon. Be generous with the salt until the broth has a really good flavor. You can also add a squeeze of lemon juice to brighten up the flavors, fresh slivered basil, more red pepper, etc.)
Ladle soup into bowls and top with crumbled cooked bacon, if desired. Enjoy!