Preheat oven. Grease a donut pan with cooking spray. Mix milk and white vinegar and let it sit.
Whisk together egg, buttermilk, vanilla, melted butter, and vinegar.
Add flour, cocoa powder, baking soda, sugar and salt and mix to combine.
Add red food coloring and mix the batter till the color is fully incorporated.
Pour the batter into a piping bag, pushing it to a corner. Cut about ¾-inch at the tip.
Pipe batter into the donut molds.
Bake until an inserted toothpick comes out clean. Transfer the donuts to a wire rack for cooling.
Prepare frosting by whisking together cream cheese, powdered sugar, vanilla and milk.
Dip the donuts in the frosting half way through. Swirl the donut so it gets coated with the frosting.
Sprinkle extra cake crumbs on top of the icing.
Enjoy the donuts!