Add all of the ingredients (through the thyme) to the slow cooker. Cover and cook on high for 4 hours or low for 8 hours.
Remove the lid and scoop out the thyme stems. Add the pasta, stir, cover and cook on LOW for 30 more minutes.
Give it a stir, taste and adjust the seasonings as needed. Serve hot with more thyme sprinkled on top.
Video
Notes
If you are sensitive to salt you can use low sodium broth or use 1/2 broth and 1/2 water.
If you have leftovers, the pasta will continue to absorb the broth as it sits in the fridge which will likely make it crumble when you reheat it. I had no problem with this, but if it will be an issue for you, you can cook the pasta separately and just add it to the soup as you eat it.