Preheat your oven to 350°F. Spray an 8½ x 4½-inch loaf pan with nonstick cooking spray to ensure an easy release, then line it with parchment paper for extra insurance. This step helps prevent sticking and makes cleanup easier.

In a large bowl, combine the entire box of dry Duncan Hines Spice Cake mix with the full can of pumpkin puree. Mix until the batter is smooth and well incorporated, with no visible lumps of dry mix. Spoon the batter into the prepared loaf pan, and smooth out the top with a spatula so the loaf bakes evenly. If you'd like an added sweet crunch, generously sprinkle cinnamon sugar or coarse sugar over the surface of the batter. Personally, I love adding cinnamon sugar for a fragrant, crispy topping!

Place the loaf pan in the preheated oven and bake for 50-60 minutes. The bread is done when a toothpick inserted into the center comes out clean or with just a few crumbs. Remove the bread from the oven and let it cool in the pan for 20 minutes, then lift it out using the parchment paper and transfer to a wire rack to cool completely before slicing. Allowing the bread to cool properly helps it set and makes slicing easier.