Preheat your oven to 350°F and grease a 9x13-inch baking dish with butter. Dice the chicken breasts into bite-sized pieces about 1-inch cubes, and set aside on a clean cutting board.

In a large mixing bowl, combine the sour cream, cream of mushroom soup, and chicken broth, whisking until smooth and well combined. Add the diced onion, minced garlic, salt, pepper, and paprika to the creamy mixture and stir thoroughly.

Fold the diced chicken pieces and frozen hashbrowns into the cream sauce along with the green beans, mixing gently until every ingredient is evenly coated. Reserve 1/2 cup of the cheddar cheese and fold the remaining cheese into the mixture.

Pour the entire mixture into your prepared baking dish, spreading it into an even layer. Bake uncovered for 30 minutes until the top begins to turn golden and the sides start bubbling at the edges.

In a small bowl, combine the breadcrumbs with the reserved cheddar cheese and fresh parsley, then sprinkle this mixture evenly over the golden chicken hashbrown casserole. Return to the oven for another 10 minutes until the topping becomes crispy and golden brown on top.

Remove from the oven and let it rest for 5 minutes before serving, allowing the sauce to set slightly and make portioning easier.