In a large mixing bowl, combine the yellow cake mix, self-rising flour, and ground cinnamon. Whisk these dry ingredients until well-blended.
Incorporate the eggs and the mashed apple pie filling into the dry mixture, stirring gently until the batter is smooth. Fold in the diced apple, being careful not to overmix.
Grease two loaf pans and divide the batter evenly between them.
Sprinkle the surface of each loaf with the prepared sugar and cinnamon mixture for a flavorful topping.
Bake in a preheated oven at 325°F (160°C) for 35 to 45 minutes, or until a toothpick inserted into the center of each loaf comes out clean.