Preheat oven to 350 degrees F (175 degrees C). Place a wire rack on top of a baking sheet.
Place pork on a work surface and cut into 1/2-inch thickness, starting 1/2 inch from the cutting board and rolling pork open while cutting until entire loin is unrolled onto the work surface. Cover loin with plastic wrap and pound loin into 1/4-inch thickness with a meat mallet.
Mix apples, bread, chicken stock, poultry seasoning, seasoned salt, and eggs together in a bowl; spread onto the loin. Roll loin around apple filling, ending with the fat cap on top. Cut stuffed pork loin in half and place on rack.
Bake in the preheated oven until pork is no longer pink in the center, about 1 hour. An instant-read thermometer inserted into the center should read at least 145 degrees F (63 degrees C).