Start by preheating your oven to 350°F (175°C). This step is vital, so the casserole cooks evenly.
Spray a 9x13-inch baking dish with non-stick cooking spray. Make sure to coat it generously, ensuring easy removal of the casserole later.
In a small skillet, melt a tablespoon of butter over medium heat. Add the minced onion and sauté until they are soft and translucent—about 5 minutes. This step enhances the dish's flavor, so don’t skip it!
In a large mixing bowl, combine the melted butter, sautéed onions, shredded hash browns, condensed chicken soup, garlic, smoked paprika, salt, black pepper, and sour cream. Mix thoroughly until everything is well combined.
Spread half of the hash brown mixture into the prepared baking dish. Layer on half of the shredded cheese, then top with the remaining hash brown mixture. Finally, sprinkle the rest of the cheese on top.
Cover the dish with aluminum foil and bake in the preheated oven for 25-30 minutes. Remove the foil and bake for an additional 15-20 minutes, or until the top is golden and bubbly.
Once done, let the casserole cool for a few minutes before serving. This cooling process allows the dish to set slightly, making it easier to cut into squares.