Preheat oven to 350?F/175?C. Grease a donut pan with butter or baking spray.

Whisk together the flour, sugar, cocoa powder, nutmeg, baking powder, baking soda, and salt in a large bowl. Combine buttermilk, egg, melted butter, and vanilla extract.

Pour buttermilk mixture into dry mixture and fold in until all incorporated. Make sure there are no flour pockets.

Pipe the batter into the cavities, filling each ? of the way. Bake for 11-13 minutes, until golden brown and springy to the touch.

After 5 minutes, take out each donut and let cool on a wire rack before pouring the next batch in. Consider re-greasing the pan before refilling it.

Combine glaze ingredients together in a medium bowl until completely smooth. Dip each cooled doughnut in and let dry on a cooling rack above a paper towel.