Prep for baking. Heat oven to 350°F and adjust rack to the middle. Line a baking sheet with parchment paper and grease parchment.
Mix dry ingredients. Combine flour, baking powder, baking soda, salt, and cinnamon in a medium bowl and whisk to break up any lumps and incorporate ingredients.
Finish the dough. Whisk eggs, granulated sugar and brown sugar in a large bowl with a whisk until lightened in color, about 2 minutes. Whisk in oil, pumpkin and vanilla until blended. Add flour mixture, and mix with a rubber spatula until incorporated.
Bake. Scoop tablespoon-sized mounds of dough onto the baking sheet, about an inch apart. Smooth the tops with a butter knife and bake until firm on top and just starting to brown on the bottom, about 12-15 minutes.
Cool. Remove cookies to a wire rack and let cool completely.
Dust. Once completely cool, dust the tops with powdered sugar.