Preheat oven to 375 degrees. Combine the flour, sugar, cocoa powder, & chocolate chips together. In a separate bowl, whisk together the eggs, vanilla extract, sour cream, vegetable oil & milk. Mix together the liquid mixture with the dry mixture until combined, being careful not to over mix.

Distribute the mixture evenly between the donut holes in your donut pan. It makes it easier if you put the batter into a ziploc bag, cut off the tip, & squeeze it in the donut tins, but it's not necessary.

Bake at 375 for 8 minutes. Let the donuts stay in the pan for a couple of minutes to cool before turning them out onto a wire rack.

While the donuts are in the oven, make the glaze. Mix together the glaze ingredients in a saucepan over low/medium heat until combined & the sugar is dissolved. Remove from the heat.

Glaze the donuts while still warm by dipping the donuts into the glaze, thoroughly coating all sides. Cool on a wire rack over a baking sheet until the glaze is set.