Preheat your oven to 375 degrees. Prepare the donut pan by spraying with baking spray.
In a medium bowl, whisk together the flour, sugar, cocoa powder, baking soda and salt. Set aside.
In a small bowl, beat the eggs then add the milk, sour cream, vanilla and canola oil. Beat until combined.
Pour the egg mixture into the dry ingredients and mix just until combined.
You can use a spoon to pour the batter into the donut pan, or you can use the following technique. Fold down the top of a gallon-size zipper bag. Stand the bag up in a bowl or measuring cup. Pour the batter into the zipper bag. Get the air out of the bag and seal it up. Carefully cut just about 1/8" of a corner of the bag. Pipe the batter into the donut pan, filling each well up about 2/3 full.
Bake the donuts for 7 to 8 minutes.
Remove from the oven and cool for about 3 minutes in the pan, then remove them and allow them to cool further on a wire rack.
Prepare the glaze by combining all of the ingredients in a medium bowl until smooth. Dip the tops of each donut into the glaze then place them back on the wire rack to set…or into your mouth for quality control.