Spray slow cooker with non-stick spray or olive oil.
Add in the potatoes, sliced sausage, and some of the shredded cheddar cheese to the crockpot. Give it a gentle toss so everything is mixed.
Add in the condensed cream of mushroom soup, sour cream, salt, pepper, garlic and cajun seasoning if using. Gently mix everything so it’s evenly coated.
Sprinkle the remaining cheddar cheese on top, cover, and cook on high for 3–4 hours (my consistency was good at 4 hours) or low for 6–7 hours.
Spoon into bowls and enjoy.