In a large pot over medium heat, heat oil. Add onions, celery, and carrots and cook until softened, 6 minutes. Add garlic and thyme and cook until fragrant, 1 minute more.
Move vegetables to one side of the pot and add chicken. Season with salt and pepper and cook until no pink remains, 6 to 8 minutes. Add stock and 1/2 cup of water and bring to a boil.
Add noodles and cook according to package instructions. Season to taste with salt and pepper. Add parsley and serve immediately.