Preheat oven to 350F. Grease 2 donut pans and set aside.
In a medium bowl, whisk sugar, pumpkin puree, maple syrup, egg, oil, buttermilk, and vanilla until smooth.
In a separate medium bowl, whisk flour, baking powder, baking soda, pumpkin pie spice, and salt. Fold flour mixture into liquid mixture until batter is just combined.
Scrape batter into a sealable bag and seal bag. Snip a corner off of the bag and pipe batter into prepared donut pans, filling each cavity about 3/4 full.
Bake donuts at 350F 12-15 minutes until donuts spring back when lightly touched. Allow donuts to cool in pans 10 minutes then transfer to a wire cooling rack to cool completely.