Preheat your oven to 400 degrees Fahrenheit. Grease a medium 12-donut donut pan with vegetable oil cooking spray or butter and set aside.
In a large bowl, whisk together the flour, sugar, baking powder, cinnamon, nutmeg and salt.
In a glass measuring cup, measure the buttermilk.
Add the eggs and vegetable oil to the buttermilk and whisk with a fork to combine and break up the eggs.
Add the wet ingredients to the dry ingredients and mix together gently with a rubber spatula just until any streaks of flour disappear. Over-mixing can make the donuts tough and rubbery, so mix gently and only as much as you need to.
Add the batter to a large piping bag and pipe the donuts into the donut pan cavities only about 1/2 to 2/3 full.
Bake at 400 degrees Fahrenheit for about 7-9 minutes, or until the donuts are just golden brown on top and lose their shine.
Cool in the donut pan for about 5 minutes before removing to a wire rack to cool completely.
Once cooled, dip the donuts in powdered sugar (use a light spritz of vegetable oil spray on the donuts if the powdered sugar needs help sticking!) and enjoy!
Store these donuts in an airtight container for up to 3 days. They are best enjoyed fresh!