Add chicken and rice and return to a simmer. Stir in peas, parsley, and sour cream; season with salt and pepper. Transfer the mixture to an 8-inch square baking dish. Top with breadcrumbs.
The chicken should literally fall off the bone. If desired, cut into bite-sized pieces and return to the pan. Drain the rice and place into bowls. To serve, generously ladle casserole onto bowls ...
For the casserole, season the chicken pieces with salt ... to dry them slightly. Mash or rice the potatoes until smooth, then stir in the butter and cream until smooth and well combined, and ...