Heat olive oil or butter in a skillet over medium heat. Add diced onion, carrots, celery, and minced garlic. Cook for about 5–7 minutes.
Place chicken breasts in the slow cooker and season with salt, black pepper, and Italian seasoning.
Add sautéed vegetables, chicken broth, and cream of chicken soup to the slow cooker. Stir until well combined.
Cover and cook on low for 6–7 hours or high for 3–4 hours.
Remove chicken breasts and shred them into bite-sized pieces before returning them to the pot.
Stir in heavy cream and uncooked egg noodles. Cover and cook on high for an additional 20–30 minutes.
Sprinkle fresh parsley over the soup before serving.