Noticing this thread, I did an experiment I have considered since I pulled the blossoms off our lavender plant in late summer. I put 4 of them in the Zassie with 18 g decaf Zoka Paladino. I didn't have it dialed in well after the Harrar Oromia so the flow rate was too high for ideal extraction. The result was espresso with an added dimension of lavender. It was well worth the experimentation. I added milk after sampling the shot and the lavender came through there as well. I remain a coffee purist and will not make a habit of it. We'll see if the effect lingers at all after one double shot ground in the Zassie and pulled through the CMA lever.

I think any dry ingredient would work better if allowed possibility to have normal contact with hot water. I would brew it separately in a little bit of hot water and then add (a bit of or whole, depending on how many shots are to be flavoured) the brew to the shot.
With cocoa, I sometimes do a sort of americano - brew a cup of cocoa and then pull a shot directly to it. If it was going to be just a shot of espresso I would sprinkle a little bit of cocoa powder on top of the shot and then stir. With cardamon I'd do it the opposite way - put the cardamon in the cup, on the bottom of it, then pull the shot onto the dry powder.
My rationale behind this advice is the nature of the discussed spices - cocoa: heavy, thick; cardamon: light, powdery; any dry leaves or flowers give their best while having contact with pure, freshly boiled hot water.

Have you ever considered making your own syrups? Like most other things, homemade syrup is worlds better than store bought. My wife got a vanilla latte from a high-end shop in town (Barista) made with fresh homemade vanilla syrup and it was really tasty! Paired with the Ethiopian espresso she had, it tasted like a blueberry waffle! Store bought syrups often taste fake and overly sugary. There is no comparison to a fresh syrup with no artificial flavor, color, or preservatives. You can even control the amount of sugar that goes into it. Do you see a parallel here to our coffee world?

p.s. cocoa is always a viable choice for a special coffee drink, but get a good quality, fair-trade cocoa

p.p.s. As I am young and recently married, I have been getting into cooking a lot in the past year. I picked up The Flavor Bible (awesome book! Check it out if you haven't already.) and there is a part that talks about picking ingredients for a dish. It mentions that their should always be a main ingredient and everything else should compliment or add to that ingredient. If an added ingredient does not make the main ingredient taste better or more like it is supposed to taste or an added ingredient, although, may have a good taste on its own, simply is distracting or overpowering, it should be left out. Also a bit extreme/purist (but who are we to judge!), one chef mentions that aside from a few exceptions, your seasoning should never be detected. How much acid, salt, or heat you used should not be obvious. "...your beans should taste like beans, and your rabbit should taste like rabbit. ...when a diner tastes your dish, all you want them to be thinking about is those beans, or that rabbit" -Sharon Hage

One of my things is cardamon ground with the beans (but I use my hario if I'm doing a favoring) and finishing with a few drops of genuine orange flower water.

So far I've done this for fun for friends with, from nice to weird, cinnamon, nutmeg, cardamom, black pepper, mustard seed (edit: which wasn't as bad as I expected).

HB wrote:Or the mypressi TWIST.

+1 on the Mypressi, you can do a lot of interesting things from using other liquids, (seems like I heard of guys experimenting with different alcoholic beverages) to adding about anything in the basket, without worry of a backflush or any other problems

Not exactly spices, but in Greece they mix ground roasted chick peas with ground coffee. They use a 1/5 ratio (1 part roasted chick peas, 5 parts coffee). Same grinder setting.

Cheers

I only skimmed this thread, but it's an interesting one. It's been a long time since I've messed with such additives, but I've made some very good drinks with freshly pan roasted fennel seeds. Put them in a pan on medium-low heat, and they'll bounce around in the pan as they dry & roast (much like pan roasting coffee). I used a blade grinder to get them finely ground, and put the fennel grounds in the middle of the shots I was pulling. Awesome straight, or with milk.

For those who drink alcohol, I highly recommend a shot of Sambuka in an 8oz latte.

Chad C. wrote:For those who drink alcohol, I highly recommend a shot of Sambuka in an 8oz latte.

It's quite off-topic, but: a great-tasting treat.
A double shot of espresso, stir in a half of spoonful of honey and add half of shotglass of Finlandia vodka. If you like it cooled, add an icecube in the end. And maybe take a triple as base.
I use heather or multiflorous honey for that, with other types it will lack on the sweetness.
Also with higher amount either of honey or vodka, it will lack balance.
Happy booze!