Preheat the oven to 350?F. Spray a donut pan with non-stick cooking spray and coat the entire donut well with a paper towel.

In a smaller bowl, combine the flour, cocoa powder, granulated sugar, baking powder, and salt. Mix until combined and set aside.

In a mixing bowl, whisk together the milk, egg, vanilla extract, and vegetable oil until well combined. Gradually add the flour mixture, mixing by hand with a spatula just until combined.

Transfer the batter to a piping bag or ziplock bag with one corner cut off, and pipe the batter evenly into the donut wells. Use a small spatula to smooth the tops if uneven.

Bake for 10-13 minutes or until a toothpick inserted in the center comes out clean. Cool the donuts for 10 minutes in the pan, then invert the pan to release them.

To make the chocolate glaze, place chocolate chips and oil in a microwave-safe bowl. Microwave for 1 minute on 50% power, stir, then heat for additional 30-second intervals until melted and smooth. Allow to cool slightly before dipping.

Dip each donut into the chocolate glaze, letting excess drip off. Add sprinkles if desired. Allow the glaze to set or enjoy immediately.