Cook Italian sausage in a large pot or dutch oven of medium heat. Once fully cooked, use a slotted spoon to remove sausage and set aside. Add celery, carrots, and yellow onion to the pan and cook for 5 minutes. Add rosemary, thyme, oregano, salt, and garlic powder and cook for another 5 minutes.
Add broth, tomato paste, and tomato sauce. Mix to combine then cover and bring to a boil. Once boiling, add the grain-free cassava elbow pasta to the pot and cook pasta for 13-15 minutes, until al dente.
Once pasta is cooked through, turn down heat and add Italian sausage back to the pot along with the fresh spinach. Cook for around 3 minutes to heat through and wilt the spinach. Top with black pepper before serving!