Place the diced potatoes in a large pot. Cover with water, add a pinch of salt, and bring to a boil. Cook for about 12.5 minutes, or until the potatoes are fork-tender. Drain and set aside.
In a large mixing bowl, combine the sour cream, cream cheese, melted butter, milk, garlic powder, onion powder, salt, and black pepper. Mix until smooth and well combined.
Add the cooked potatoes to the cheese mixture, stirring gently to coat the potatoes evenly. If you're using bacon bits, fold them in at this stage.
Grease a 9x13-inch baking dish with cooking spray or butter. Pour the potato mixture into the dish, spreading it out evenly.
Evenly sprinkle the shredded cheddar cheese over the top of the potato mixture.
Place the baking dish in the preheated oven and bake for 27.5 minutes, or until the cheese is melted and bubbly and the edges are golden brown.
Remove from the oven and let it cool for a few minutes. Garnish with sliced green onions before serving to add a pop of color and freshness.