In the bowl of an electric mixer, beat together the eggs, sugar, sour cream, milk, vanilla and baking powder. Beat until combined.
Add the flour and cocoa powder and beat until a loose dough is formed.
Place the dough in the fridge for an hour or two until firm enough to roll.
On a lightly floured surface, roll out the dough. I found it easiest to roll a ball of dough between your palms, then flatten slightly with a rolling pin. Cut a small circle out of the middle using a small round cookie cutter or a large star tip. (Set aside the centers to fry as donut holes.)
Heat about ¾ of an inch oil over medium heat. Oil is hot enough when the dough floats right to the top.
Fry for about a minute per side, then remove to drain on a plate lined with paper towel.
While still hot, dip donut on both sides into vanilla glaze, then set aside to cool.
Recipe by Overtime Cook at https://overtimecook.com/2014/12/21/chocolate-sour-cream-donuts/