Preheat the oven to 325°F. Spray a 13 x 9 inch baking dish with cooking spray.
In a large mixing bowl, mix together hash browns, onion soup, sour cream, dressing mix, pepper and chopped green onions.
Stir everything until the ingredients are evenly distributed.
Add 4 tablespoons (about 2/3) melted butter and 1 1/2 cups of shredded white cheddar cheese. Mix well.
Pour the mixture into the baking dish and drizzle with the remaining 2 tablespoons of melted butter.
Sprinkle 1/2 cup of cheese on top then spread the crushed ranch flavored potato chips evenly over it all.
Bake for 1 hour and 20-25 minutes until golden and bubbly.
Let stand 5 minutes, then serve.