In a skillet over medium heat, cook bacon until golden and crisp. With a slotted spoon, remove from pan and drain on paper towels.
In a bowl, whisk together sour cream and ranch dressing mix.
Add hash browns, 2 cups of the cheese, bacon crumbles, and green onions. You can leave about 1 tablespoon of bacon and green onions to garnish potatoes once cooked. Transfer into a baking dish.
Bake, uncovered, in a 400 F oven for about 40 to 50 minutes or until cooked through.
Sprinkle remaining 1 cup cheese on top and bake for another 5 to 10 minutes or cheese is melted.
Remove from heat and garnish with additional bacon crumbles and green onions, if desired. Serve hot.
Notes
For a smoother melt, use freshly grated cheese instead of pre-shredded bagged cheese, which contains additives that result in a grainy texture.