Preheat oven to 425 degrees, and lightly spray donut pan with non-stick spray.
In a medium mixing bowl, whisk together flour, sugar, cocoa powder, baking powder, cinnamon, and salt. Stir in vanilla extract, milk, eggs, and melted butter until combined. Batter will be thick. Stir in chocolate chips.
Pipe into the pan with a plastic baggie or piping bag, or spoon evenly into the donut pan. Bake for 7-9 minutes. Cool in the pans for about 5 minutes before removing. Cool completely before icing.
Combine all of the icing ingredients in a small bowl. If you want a thicker glaze add more powdered sugar, if you need to thin it out, add more milk in small amounts at a time. Dip each donut or drizzle over the top. Best if enjoyed immediately.