Preheat the Oven: Set your oven to 350°F (175°C) to get it ready for baking.

Sauté the Onions and Garlic: In a large skillet, heat the olive oil over medium heat. Add the diced onion and minced garlic, sautéing until the onion becomes translucent (about 3-5 minutes).

Combine the Ingredients: In a large bowl, mix together the frozen hashbrowns, onion and garlic sauté, cheddar cheese, sour cream, cream of chicken soup, salt, and pepper until well combined.

Transfer to Baking Dish: Pour the mixture into a greased 9x13 inch baking dish, spreading evenly.

Bake: Place the dish in the preheated oven and bake for 45-50 minutes or until heated through and golden on top.

Garnish and Serve: Sprinkle with chopped green onions before serving to add a nice fresh touch!