Add the smoked sausage, diced Yukon Gold potatoes, diced onion, minced garlic, chicken broth, and cream of chicken soup to your crockpot.
Season with Cajun seasoning, Kinder's Buttery Garlic & Herb Seasoning, garlic salt, garlic powder, onion powder, and black pepper. Stir everything together until combined.
Cover and cook on HIGH for 4 to 5 hours or LOW for 7 to 8 hours, until the potatoes are fork tender.
Stir in the cream cheese until it is completely melted into the soup.
Add the heavy cream and shredded cheddar cheese. Stir until the cheese melts and the soup is smooth and creamy.
In a small bowl, whisk together the cornstarch and cold water until smooth.
Stir the cornstarch slurry into the soup. Cover and cook for another 10 to 15 minutes, or until the soup has thickened.
Give the soup one final stir, garnish with chopped green onions if desired, and serve hot with crusty bread.