Preheat oven to 400 degrees. Grease a 6-count donut pan well.
In a large bowl, sift together flour, sugar, baking powder, salt, and spices.
Make a well in the center of the dry ingredients, and add in add in the egg, buttermilk, and vanilla extract. Gently stir until just combined (batter will be very thick).
Add in sour cream, butter, and pumpkin puree. Mix until well combined.
Lastly, add in chocolate chips.
Spoon or pipe batter into the donut pan.
Bake donuts for 10-12 minutes, or until the donuts have risen and the tops of the donuts 'spring' back when lightly touched.
Allow to cool for at least 5 minutes before removing from the tray.
In a bowl, whisk powdered sugar, cinnamon, and espresso powder with vanilla extract and 2 Tbsp of milk until smooth (if the glaze seems too thick, add in the last Tbsp of milk).
When ready to glaze the donuts, give the glaze a quick stir, then dunk each donut about halfway into the glaze. Place donuts on a wire cooling rack to give the glaze time to set (about 10 minutes).
Enjoy!