In a large Dutch oven over medium heat, brown sausage until cooked through. Add onions, garlic and red pepper flakes and cook for an additional 4-5 minutes, stirring frequently. Drain excess fat and return pot to the stove.
Add potatoes, chicken broth and water to the sausage mixture. Continue cooking over medium heat until the potatoes are cooked through.
Add heavy cream and kale and continue cooking for an additional 10-15 minutes. Salt and pepper to taste.
Notes
To kick things up a notch, substitute hot italian sausage for the sweet and increase the amount of red pepper flakes. Please note the color of the soup may take on an orange color with this substitution due to the spices in hot sausage.