Heat olive oil in a large pot over medium heat.
Add diced onions, minced garlic, Italian seasoning, chili flakes, salt, and pepper. Sauté for about 5 minutes until onions soften.
Add Italian sausage, breaking it into smaller pieces, and cook until browned.
Stir in arrowroot starch, tapioca flour, or cornstarch (if using), diced potatoes, chopped kale, chicken broth, cream or milk, and grated parmesan cheese. Bring to a gentle boil.
Reduce heat, cover, and simmer for 15 minutes.
Squeeze lemon juice over the soup and sprinkle with more parmesan cheese before serving. Enjoy the warmth and goodness! Store any leftovers in the fridge for up to a week in a sealed container.