Preheat your oven to 350°F (175°C) and grease a 9×13-inch baking dish.
In a large mixing bowl, combine cream of chicken soup, sour cream, 1½ cups of shredded cheddar cheese, chopped green onions, garlic powder, black pepper, and paprika. Stir until smooth and well-integrated.
Fold in the thawed hash brown potatoes, making sure they're evenly coated in the mixture.
Gently incorporate the sliced kielbasa sausage, then spread everything into your prepared baking dish.
Sprinkle the remaining ½ cup of cheddar cheese over the top.
Optional: Mix 2 tablespoons of melted butter with 1 cup of crushed cornflakes or Ritz crackers and scatter over the cheese for a crunchy topping.
Bake until hot and bubbly, approximately 45-50 minutes.