Samuel Adams Chocolate Bock can be located in the Sam Adams winter mix pack.
It is a brownish towards blackish color with a limited head that dissipates quickly. I was really looking forward to the smell, but I find it to be faint cocoa. I would like it more if the aroma was stronger.
It tastes slightly malty and dry (almost dusty) just before the earthy, slightly sweet cocoa taste hits you. That part is surprising and yummy. It is not particularly smooth, or deeply malty. Not much like a bock to me, very much lighter than a bock. Nice for a one off beer, the cocoa taste is quite intriguing and tasty.
I cannot see myself wanting more than one of these at a time, but I like it enough to buy another winter mix pack which is as far as I can tell the only way to get two of these at the moment.