Rinse hens with cold water; pat dry.
Combine 1 tsp. salt and 1/4 tsp. pepper. Sprinkle cavities and outside of hens evenly with salt mixture. Set hens aside.
Peel apple, and cut into 1-inch cubes.
Combine apple, remaining 1/2 tsp. salt, remaining 1/4 tsp. pepper, squash, and next 4 ingredients in a medium bowl, tossing to coat.
Stuff hen cavities with apple mixture; place extra mixture in a lightly greased 11- x 7-inch baking dish. Place hens on top of apple mixture; cover tightly with aluminum foil.
Bake at 350° for 45 minutes; remove foil, and bake 45 more minutes or until meat juices run clear and an instant-read thermometer inserted into thigh registers 180° and internal temperature in center of stuffing registers 190°. Remove from oven; let stand 5 minutes before serving.