Preheat the oven to 350°F (175°C) and grease a donut pan generously with cooking spray.
In a large bowl, whisk together the flour, sugar, baking powder, cinnamon, and any other preferred spices.
In another bowl, combine pumpkin puree, egg, milk, and melted butter. Whisk until smooth.
Pour the wet mixture into the dry ingredients and gently fold until just combined.
Fill each donut mold about ¾ full.
Bake for about 10-12 minutes or until a toothpick comes out clean.
Prepare the cinnamon sugar mixture while the donuts bake.
Allow the donuts to cool for about 5 minutes, then transfer to a wire rack and roll in the cinnamon sugar mixture.
Serve fresh or store in an airtight container for up to three days.