Foody Friday: best chocolate cake recipe

Last week it was my technician's birthday, and I made her her favorite: chocolate cake (this one with chocolate sour cream frosting, a perfect not-too-sweet option for a rich cake). Every time I make chocolate cake I try a different recipe. I'm on a quest for the best chocolate cake recipe.

This cake wasn't it. It was good, but it was too dense. I'm picky about my cakes.
The perfect recipe needs to be:
- Firm, dense, but light, with a completely even crumb and no large air bubbles (like a cake mix would have - yuck).
- Rich chocolate taste, not cocoa.
- Easy to make: no double boilers, no separating eggs, no changing oven temps half way through, no creaming butter.
- Good for layers: cake doesn't tend to stick to pans
- Contains ingredients I have on hand (so requires cocoa, not chocolate - but it has to taste like chocolate, not cocoa. Got it?).

So far the closest I've come is this recipe, with a few alterations. (Also, that particular recipe [with the buttercream and ganache] is heavenly and makes a beautiful graphic statement cake - amazing for celebrations that need something a little more grown-up than birthday cake.)

I always have two secret ingredients when I make chocolate cake: one addition, and one substitution.
The first is black pepper. Adding a pinch of finely ground black pepper turns cocoa powder somehow into rich and delicious chocolate.
The substitution is sour cream for all or part of the oil. Deliciously moist and no residual oil taste.

But really, I'm still hunting for the perfect recipe. So if you have one, please share!