Preheat the oven to 350°F and set the oven rack to the middle position. For mini loaf pans, lightly grease them and line with parchment paper, allowing some to overhang the sides to help remove the bread. If using a brownie pan, line 5 of the wells with parchment strips that extend over the sides.

In a medium-sized mixing bowl, whisk together the egg, granulated sugar, brown sugar, pumpkin, oil, and vanilla extract until the mixture is smooth and well combined.

Sift the flour, baking powder, baking soda, pumpkin pie spice, and salt over the wet ingredients. Whisk the mixture gently until no streaks of dry ingredients remain.

Evenly divide the batter into the prepared pans. Generously sprinkle cinnamon sugar over the top of the batter. Using a toothpick or knife, lightly swirl the cinnamon sugar into the top layer of the batter.

Bake according to the pan size: for brownie pans, bake for 20 to 23 minutes; for mini loaf pans, bake for 28 to 30 minutes. The bread is done when a toothpick inserted into the center comes out mostly clean.

Allow the bread to cool in the pan on a wire rack for 10 to 15 minutes. Then, carefully lift the bread out using the parchment sling and let it cool completely on the rack.