Preheat oven to 425 degrees F.
Spray donut pan with non-stick cooking spray. Set aside.
In a medium mixing bowl, whisk together flour, sugars, baking powder, and salt.
In a large measuring cup, whisk together buttermilk, pumpkin, vanilla and oil.
Add the wet ingredients to the dry ingredients and sitr until combined. Do not overmix.
Place the batter in a ziploc bag and close. Snip one corner of the bag.
Pipe the batter out into the prepared pan, filling the donut cavities 2/3 full.
Bake the donuts for 8 to 9 minutes (for me the magic number was 9). The bottom of the donuts should be golden brown and the tops should be light.
Cool the donuts in the pan for 10 minutes. Transfer onto a cooling rack.
Cool completely before glazing.
!to make the glaze:
Place chocolate, butter and corn syrup in a microwave safe small bowl. Microwave in 20 second increments until melted. Stir until smooth. Add hot water and stir again.
Dip each donut in the glaze and place back on a wire rack.
Decorate with sprinkles.
Store in an air tight container in a room temperature for up to 2 days.