1. Preheat oven to 350°F.
2. Lightly grease a donut pan with cooking spray.
3. Using a kitchen towel, smear is all around the mold and wipe off the excess.
4. Mix milk and white vinegar and let it sit while you gather the ingredients. In a large mixing bowl add egg, buttermilk, vanilla, melted butter, food coloring and vinegar. Using an electric hand mixer or a large wire whisk, beat until well combined.
5. Add dry ingredients, including flour, cocoa powder, baking soda, sugar and salt, in a sieve and sift into the wet ingredients. Mix well to combine.
6. Pour batter into a gallon size ziplock bag (or large piping bag), pushing it to a corner. Squeeze the air out of the bag and twist till you get a firm grip on the bag. Cut about ¾-inch at the tip. Pipe batter into the donut mold until about ½ full. Pipe any excess batter in an oven-safe ramekin. We will bake this and use for garnishing the donuts.
7. Bake at 350°F for 9-10 minutes, or until an inserted toothpick comes out clean.
8. Using a paring knife, carefully transfer the donuts on a wire rack for cooling, for about 30 minutes.
9. While the donuts cool, prepare the frosting by whisking together softened cream cheese, powdered sugar, vanilla, and milk. Adjust the quantity of milk-based on consistency. We want this frosting to be like pancake batter.
10. When the donuts have cooled, dip them in the frosting halfway through. Swirl the donut so it gets coated with the frosting.
11. Place the donut back on the wire rack for the icing to set.
12. Crumble the excess batter that we baked in a ramekin. Sprinkle the crumbs on top of the icing. This step is optional but makes for a pretty presentation.
13. Enjoy the donuts!

Recipe Notes: The frosting can be made 2-3 days ahead and refrigerated. Remove from refrigerator 30 minutes before icing the donuts.