In a mixing bowl, whisk the flour, cocoa powder, baking powder, baking soda, salt, and chocolate chips. Mix until the chocolate chips are well coated with the dry ingredients.
In a large mixing bowl, mix the egg and granulated sugar until well combined.
Add the sour cream and melted butter, and continue mixing.
Add in the flour mixture alternating with the milk to the egg mixture.
Continue mixing until all the ingredients are incorporated and you have no dry flour left. Do not over-mix.
Fill the donut pan about 3/4 full each. This can be done with a spoon or a piping bag. The piping bag works the best, but you want to do this without a tip on the end because of the chocolate chips.
Bake in a preheated oven for 8-10 minutes or until when a toothpick is inserted in the donuts, it comes out clean.
Allow the donuts to cool for 2-3 minutes in the pan.
Remove from the pan and cool completely on a cooling rack before adding toppings.
Notes
These can be topped with any icing or sprinkles that you prefer.Store in an airtight container for 3-4 days or in the fridge for up to a week.