Slice the green onions. Spray a 9x13 pan with cooking spray. Open the bag of potatoes and pour the potatoes into a large mixing bowl. Heat the 3 Tbs. butter and pour over the potatoes. Mix and then add the sour cream and cream of chicken soup and combine with the potatoes until evenly distributed. Add the sliced green onions, dry ranch dressing mix, garlic powder and mix. Pour the potato mixture into the 9x13 pan and spread out evenly. Top the potatoes with the shredded cheese & panko crumbs. You can also use crushed corn flakes instead of panko crumbs if you prefer that texture. Drizzle the top of the casserole with the 4 Tbs. melted butter. Bake at 350 for 30 minutes, until brown & bubbly. Garnish with fresh or dried parsley.