Spray a donut pan with non-stick spray and set aside.
In a large bowl, toss together the flour, Dutch processed cocoa, baking powder, and salt. Set aside.
In a medium size bowl, whisk together the brown sugar, butter, and milk until no sugar lumps remain. Add the egg and the vanilla extract and whisk again until everything is incorporated. Add the wet ingredients to the dry ingredients and stir until just combined. Gently stir in mini chocolate chips.
Transfer batter to a large zip top bag, snip the corner off, and pipe batter evenly into donut wells, filling them ⅔ to ¾ full. You may also use a spoon.
Bake the donuts 8-10 minutes or until donuts are set. Cool completely on a wire rack before dipping into glaze.
Combine all of the ingredients into a medium size bowl. Dunk donuts into glaze one by one. Transfer to wire rack over a baking sheet or wax paper to catch glaze drippings.
Dunk donuts a second time with remaining glaze. Decorate with more mini chocolate chips, if desired. Donuts taste the freshest the same day they are baked, but can be stored covered at room temperature up to 2 days.