Preheat your oven to 350 degrees/F and prepare a donut baking pan by spraying generously with non-stick spray.
In the bowl of a stand mixer equipped with a whisk attachment, combine the flour, sugar, cocoa powder, baking soda, and salt. Whisk to combine.
In a large glass measuring cup, add the vegetable oil, buttermilk, egg, and vanilla and whisk with a fork until well combined.
With the mixer on low speed, slowly pour the wet ingredients into the dry. Mix until just combined. Be sure to scrape the sides and bottom of the bowl to make sure all the ingredients are incorporated.
Prepare a piping bag with a large round tip, or a large Ziplock bag with the corner removed. Add the batter to your bag being careful to not let the batter run out of the hole.
Pipe the batter into each donut mold, filling about 2/3 full.
Once you have all the batter piped, gently tap the tray against the counter 4-5 times to remove any air bubbles.
Bake for 10-13 minutes or until a toothpick inserted in the thickest part of the donut comes out clean.
Remove from the oven and allow to cool in the pan for 5 minutes before inverting onto a wire rack to cool completely.
Prepare the glaze by adding the chocolate, butter, corn syrup, and water into a microwave safe bowl and heat on 30 second increments, stirring in between, until melted and smooth.
Once the donuts are cool, dip them, top side down, into the glaze and place face up on a wire rack to harden. Sprinkle with Jimmie sprinkles
Serve and enjoy!