Preheat oven to 350°F. Spray a 24-count mini muffin pan well with nonstick cooking spray and set aside.
In a large mixing bowl, sift together the flour, cocoa powder, baking soda, and salt. Whisk until well combined and set aside.
In a separate mixing bowl, mix together the buttermilk, sugar, melted butter, egg, vanilla, red food coloring, and vinegar until fully combined. Combine the wet and dry ingredients and mix until just combined, making sure not to over mix the batter.
Evenly distribute the batter between all 24 cavities of the mini muffin pan, a piping bag works really well for this part. Bake at 350°F for 10-12 minutes or until a toothpick inserted into the donut hole comes out clean. Remove from the oven and cool in the pan for 5-10 minutes, then remove the donut holes from the pan and transfer to a wire rack to cool.
To make the glaze:
Add the cream cheese, powdered sugar, vanilla, and milk to a medium sized mixing bowl and mix until fully combined and no lumps remain. Dip each donut hole into the glaze and transfer back to the wire rack to allow the glaze to harden.