Prepare oven and baking dish: Preheat oven to 350°F. Lightly grease a 9- x 13-inch or 3 qt. baking dish with cooking spray.
Mix wet ingredients: Combine the cream cheese, sour cream, ricotta cheese, cream of chicken soup, salt, garlic powder, and onion powder in a large mixing bowl, stirring with a whisk.
Add hash browns: Fold in the thawed hash brown potatoes, Cheddar cheese, and most of the green onions to the bowl, reserving about 2 tablespoons onions for garnish.
Add to baking dish: Spoon the mixture into prepared dish, and spread into an even layer.
Make cracker topping: Combine the melted butter and crushed crackers in a medium mixing bowl; stir to coat. Sprinkle the butter-coated crackers evenly over the potato mixture.
Bake casserole: Bake in preheated oven for 50-55 minutes, or until bubbly around the edges.
Add garnishes and serve: Sprinkle reserved green onions, parsley, and black pepper evenly over the casserole.
