First prepare the beans. Cover beans with cold water and soak overnight or 6-8 hours, then drain and rinse.
Combine beans in a large stock pot and cover with water. Bring to a boil, then reduce heat slightly and simmer for 1 hour, stirring occasionally until beans are tender and cooked through. Drain beans. *The following instructions are for using an Instant Pot. For slow cooker instructions, check out the recipe notes.
Preheat your instant pot using the "saute" setting, then add Italian sausage, and onions and saute for 3-5 minutes until sausage is browned. Add garlic and cook 1-2 minutes longer until fragrant.
Switch instant pot to the "soup" setting. Add chicken broth, tomato sauce, diced tomatoes, celery, carrots, salt, pepper, crushed red pepper flakes, beans and Italian seasoning and stir to combine.
Lock the lid in place and set the pressure release to "sealing". Cook on high pressure for 10 minutes. Allow the pot to sit for 3-4 minutes and then turn the release valve for a "quick release."
Stir in ditalini pasta, garnish with cracked black pepper, fresh basil, and grated parmesan cheese if desired and serve.