Preheat oven to 350 degrees. Grease two 6-well donut pans with butter or oil.
In a bowl, whisk together eggs, sugar, vanilla, and butter until smooth. Whisk in buttermilk and red food coloring.
In a separate small bowl, sift flour, cocoa powder, baking powder, and salt. Fold into wet ingredients until just combined. Do not overmix!
Snip off a corner of a large ziptop bag, or use a pastry bag, and scoop in batter. Pipe into donut pans. Bake 8-10 minutes until tops are set and the donuts feel fairly firm to the touch. Let cool in the pans for 5-10 minutes, then pop onto a wire rack to cool completely.
To make the frosting: with a stand or hand mixer, whip the cream cheese, butter, powdered sugar, vanilla, and 1 tablespoon heavy cream until silky. If needed, whip in an additional tablespoon of heavy cream to reach the necessary texture.
Toss Oreos into a ziptop bag and seal tightly, removing all air from the bag. Smash with some firm utensil: I actually used the head of a can opener. A rolling pin, a meat mallet, or similar instrument works well. The pieces should be very small, basically crumbs.
Frost each donut with a flat headed frosting knife, leaving the hole open as desired. Sprinkle half (or all!) of each with crushed Oreos. 10/10 recommend serving dunked in coffee.