Preheat oven to 350 degrees. Grease a mini donut pan with cooking spray.
In a large mixing bowl, add in oil and sugar. Whisk until combined.
Add in the eggs and continue whisking until thoroughly incorporated.
Add in the heavy cream, vinegar, and vanilla and whisk until combined.
In a separate bowl, sift the cocoa powder, flour, baking soda, baking powder, and salt.
Pour all the dry ingredients into the wet ingredients and whisk until everything is incorporated.
Pour the batter into a piping bag or ziploc bag, cut a very small hole and squeeze batter into each donut shape in the pan. Give the pan a tap. Place into the oven for 5 and ½ minutes or until done.
Place the candy melts into a microwave-safe bowl. Microwave for 30 second intervals until melted. Using a spoon, flick the chocolate over each donut. Finish the donuts off with adding sprinkles.