In a large skillet over medium-high heat, brown and crumble hot Italian sausage, about 5-8 minutes. Add onion and garlic and cook for an additional 2-3 minutes or until some of the onion begins to turn opaque (no need to cook onion completely at this point). Drain grease from skillet.
In a large crockpot, add cooked sausage and veggies and diced potato. Season with salt and pepper, to taste. Pour chicken broth on top. There should be enough broth to cover the tops of the potatoes; if there isn’t, add up to 2 cups water.
Gently stir ingredients, cover crock pot, and cook on LOW for 5-6 hours or on HIGH for 3-4 hours.
Remove lid from crock pot and add kale and heavy whipping cream, then stir to combine.
Cover crock pot and cook on HIGH for another 30 minutes.
Serve zuppa toscana immediately with shredded parmesan cheese as garnish.