Preheat the oven to 350°F.
Line a muffin pan with paper liners and lightly coat the liners with nonstick spray.
Whisk the flour and baking powder together in a medium bowl.
In a large bowl, whisk the pumpkin, oil, eggs, pumpkin pie spice, sugar, baking soda, and salt until smooth. Add the flour mixture and whisk just until combined; do not overmix.
Mix the topping sugar and cinnamon in a small bowl.
Divide the batter among the prepared cups and sprinkle each muffin with cinnamon sugar.
Bake for 25 to 30 minutes, until a toothpick inserted in the center comes out clean.
Let the muffins stand for 5 minutes, then transfer them to a rack to cool completely.