Recently received another request for this. Thanks to Smithy for retrieving it from those old files!
But after some comments that this recipe isn't "chocolatety" enough, I do want to add a very strong caveat:
Do not add additional chocolate to this recipe.
If you want a chocolate cake, then make a chocolate cake!
If you want a Red Velvet Cake, then make a Red Velvet Cake!
A Red Velvet Cake is NOT a chocolate cake. It's a tangy cake made with vinegar and buttermilk. A very little chocolate is added to give it a rich undertone. Chocolate is a strong flavor. When you add more cocoa powder to the amount called for (which is minimal in the best Red Velvet recipes), you don't create a delicious chocolate cake. You simply ruin the Red Velvet Cake by overpowering the tang of the vinegar and buttermilk.
I repeat. If you want a chocolate cake, make a chocolate cake.
Which a Red Velvet Cake is not.