Prep the crockpot: Lightly spray the inside of your slow cooker with nonstick cooking spray for easy cleanup.
Mix the sauce: In a large bowl, whisk together cream of chicken soup, sour cream, chicken broth, melted butter, garlic powder, smoked paprika, salt, and pepper until smooth.
Add potatoes and onion: Stir the frozen hash browns and diced onion into the sauce until everything is well-coated.
Layer in the crockpot: Pour the potato mixture into the slow cooker.
Fold in half of the shredded cheddar cheese. Top with sliced kielbasa.
Cook low and slow: Cover and cook on Low for 5–6 hours or on High for 2.5–3.5 hours, until the potatoes are tender and creamy. Avoid opening the lid too often.
Add more cheese: Sprinkle the remaining cheddar over the top during the last 10–15 minutes of cooking.
Cover until melted.
Finish and serve: Taste and adjust seasoning if needed. Garnish with sliced green onions. Serve hot with a simple salad, steamed veggies, or crusty bread.