Preheat oven to 350°F. Lightly grease a donut pan with cooking spray. Using a kitchen towel, smear it in the mold and wipe off the excess. Mix milk and white vinegar and let it sit while you gather the ingredients (skip this step if using buttermilk).
In a large mixing bowl add egg, buttermilk, vanilla, melted butter, food coloring and vinegar. Using a electric hand mixer or a large whisk, beat until well combined.
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.
Add red food coloring and mix the batter till the color is fully incorporated.
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.
Bake at 350°F for 9-10 minutes, or until an inserted toothpick comes out clean. Wait 5 minutes, then using a pairing knife, carefully transfer the donuts on a wire rack for cooling, for about 30 minutes.
White the donuts cool, prepare the frosting by whisking together cream cheese, powdered sugar, vanilla and milk. Adjust the quantity of milk based on the consistency. We want this frosting to be like pancake batter.
When the donuts have cooled, dip them in the frosting half way through. Swirl the donut so it gets coated with the frosting. Place the donut back on the wire rack for the icing to set.
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. Enjoy the donuts!
Ingredient temperature: For best results, egg, butter and cream cheese should be at room temperature. This will ensure that all the ingredients mix smoothly.
Buttermilk:If you want to use buttermilk, use an equal quantity instead of combining milk with vinegar.
Frosting thickness: Adjust the quantity of milk based on thickness of frosting. It should be of the same consistency as pancake batter. If you'd like more of a glaze than a thick frosting, add a little milk at a time until you reach your desired consistency.
Frosting notes: Instead of dipping the donut in the cream cheese frosting, you can alternatively pipe the frosting in a bag. Drizzle the frosting all over the donuts in a zig-zag pattern.
Food coloring notes: When dealing with food coloring, it is best to wear food-grade gloves and protect your kitchen counter with a paper towel.
Note: The nutrition facts below are my estimates. If you are following any diet plan, I recommend cross-checking with your preferred nutrition calculator.