In a large pot over medium heat, cook the sausage until browned and crumbly, about 5-6 minutes. Transfer the sausage to a plate and drain any excess grease.
In the same pot, melt the butter. Add the diced onion and cook until translucent, about 3-4 minutes. Stir in the minced garlic and sauté for another minute. Make sure not to burn it.
Pour in the chicken broth and water, then add the potatoes, salt, and pepper. Bring to a boil, then reduce the heat to a simmer. Cook until the potatoes are tender, about 10-15 minutes. They are done when a fork easily pierces the potatoes.
Add the kale to the pot and cook until it turns bright green (about 2-3 minutes). Pour in the heavy cream and return the cooked sausage to the pot. Warm through, adjust seasoning.
Pour the hot soup into bowls. You can top it up with crumbled bacon, a generous sprinkle of Parmesan cheese and serve with a side of bread (preferably crusty!).