Preheat oven to 350°F.
Spray a donut pan with baking spray.
In a large bowl, mix oil, eggs, sugar, pumpkin, spices, salt and baking powder until smooth with a wooden spoon or spatula.
Add flour, stirring just until smooth.
Spoon the mixture into a ziploc bag or icing bag, which makes it easier to fill the donut pans.
Fill the wells of the pan about ½ full - don't over-fill.
Bake the donuts for 15 minutes or until they feel firm.
Remove donuts from the oven, and allow to cool for 5 minutes. Transfer donuts to a rack to cool.
While donuts are still warm, gently dip them into the sugar/cinnamon mixture or the glaze.
Cool completely and store in an airtight container at room temperature for several days. Inspired by King Arthur Flour.