Dice the onion, bell pepper, and carrots. Open the canned tomatoes and measure out the chicken broth and seasonings. This ensures a smooth cooking process.
Add chicken, vegetables, tomatoes, broth, and seasonings to the slow cooker. Stir gently to mix everything evenly.
Cover and cook on low for 8–10 hours. The chicken will become tender and soak up all the Italian flavors.
Remove the chicken and shred it with two forks. Return it to the crock pot and stir to combine with the broth and vegetables.
Stir in the uncooked rotini, cover, and cook on high for 20–30 minutes until the pasta is tender.
Season with extra salt, pepper, and a sprinkle of Parmesan. Serve with garlic toast for a comforting meal.