Let's make a Black Russian fit for the exacting standards of a Romanian's slave galley. So :

Making the Coffee Liqueur

You need (at least) one bottle of straight ethyl alcohol. Here in Argentina this is sold in the Pharmacy, a liter of 98%ⁱ corn distillate going for a pittance. If your place doesn't have it - fucking move.

You need (at least) one kilogram of fine coffeeⁱⁱ for ten liters of straight alcohol. The grind depends on how much patience you have versus how good filters you have. If your filters suck use a coarser grind and have more patience. This discussion will presume a medium-fine grind and a common reusable coffee filter, adjust accordingly.

You will need a kitchen robot, capable of making milkshakes ; as well as some sort of carafe. Put the reusable filter atop the carafe and you're good to go.

Once these collected, the procedure is relatively simple - but first, for the love of all that is holy, make sure you find yourself in a well ventilated room with no open flame nearby. Alcohol is extremely flammable. Burning three liters of alcohol puts out the same heat as burning two liters of gasoline ; that's a little over 17 MJ per liter.

Anyway, put the alcohol in the blender, dump the coffee grinds in, close the lid and set it to the lowest stir speed. Let it go like this for a few minutes, then turn it off for 10-15 minutes, then back on for a few minutes, then back off for 10-15. Do not overheat the engineⁱⁱⁱ ; do not start a fire ; do not forget about it and go shopping etcetera.

After sufficient passes (which in the case we're considering is about six) you're done : pour the resulting mess through the filter into the carafe, and bottle it. That's it and that's all, you now have coffee liqueur for the purpose of making Black Russians.

You do not add sugar. Not because it is illegal to add sugar, but because it is premature. You don't know yet how much sugar you actually want ; maybe it's hot one day so you'll want less ; maybe you finally decide to go on that diet (alcohol, as everyone knows, has no calories) ; maybe you start serving it to kids and they want more.

You do not add vanilla or whatever other flavouring. Stop being a Windows head. You want a few, simple tools that you can then combine and use as needed rather than a bulky monolith of everything that works for one thing that somebody thought someone may want at some point but meanwhile practice has thoroughly invalidated. There is no reason to have vanilla in your coffee liqueur ; if you want vanilla extract in your final product, add vanilla extract in your final product ; and if you have vanilla bean first extract it and then store the extract (the procedure is really not so different).

You do not "age" coffee grinds, what the everloving fuck nonsense is this. Coffee grinds do not age. The process through which things age involves molds. Cheeses age because they rot in a palatable way ; meats age because they rot in a palatable way. Aging coffee grinds is exactly equivalent to aging your bath water.

You do not use water to make liqueur. The reason is very simple : if your final product is going to be a mix of two different things, one being about 12 times a better solvent than the other, you will use the better solvent and dilute with the worse solvent ; not the other way around. Using water to extract the coffee and then dilute with alcohol is exactly like using your feet to push the car uphill. Use your brain instead of your feet.

Anyway, that's it, bottle in a tight locking glass bottle - straight alcohol escapes like Eau de Vie - and you're done. Do not use plastic, it's bad for the environment and worse for you.

Making the Cocktail

Use a quantity^iv of the Coffee Liqueur from the above, along some sugar, some flavouring (vanilla extract ?) and ice cubes.

Simple! But since our version of Coffee Liquor is stiffer than Italian Ristretto you may want to tone it down with something else - such as for instance Havana Club Anejo 7 yo, or anything else you happen to have around the house.

Enjoy!

1. That's about 171.5 / 196 "proof", for the weird schmucks that gotta multiply numbers with random parameters for no practical reason. [↩]
2. I do mean fine - Costa Rica level fine, Sumatra level fine. If you buy your coffee by brand name rather than by origin appelation you're already doing it wrong. [↩]
3. The grinds friction will provide enough heat to get the mixture to a very reasonable 30-40 degrees. This is safe - alcohol boils at 78.

   The bottom of the pot should feel warm to the touch - but no more. If it heats past that you're - quite literally - playing with fire. [↩]

4. About a spoonfull should do. [↩]