Add the cream of mushroom soup, milk, sour cream, seasonings and shredded cheese to the bottom of the crockpot. Use a wooden spoon or spatula to stir the ingredients until well combined.
21 oz. condensed cream of mushroom soup, ¾ cup milk, ¼ cup sour cream, ½ tsp garlic powder, ½ tsp kosher salt, ½ tsp ground black pepper, ½ cup freshly shredded Parmesan cheese