My heart bleeds for those with lactose intolerance. It is a terrible affliction, but the pain can be lessened and the problem can be solved by realizing the awesome power of the egg yolk. Some cultures, often those stricken by poverty, thicken their coffee with yolks. I started doing it years ago by making simple bombardinos then an old Italian woman I came across (Dante’s aunt), told me her mother used to serve her the same, but with fernet when she was a little girl in the old country.
Some fear bombardinos or advocaats because they believe the eggs are raw, but harnessing the idea of a fluid gel they are likely pasteurized, though it does remove a little bit of the myth and the adventure (fluid gels are not so easy to explain, but Modernist Cuisine does a really good job).
Here is my take on the fernet bombardino:
250 mL of fernet branca
40 g non aromatic white sugar (this brings up fernet’s sugar to about 165 g/L)
slightly more sugar can be added to bring the dissolved volume up to an even 300 mL if you like even math which I ended up doing.
200 mL of egg yolks (to yield 187.5 mL because some with cling to the bag) cooked sous-vide at 65°C for 35 minutes to pasteurize.
Fernet has an alcohol content of 39% so when we add sugar with a dissolved volume of 50 mL to 250 mL of fernet we end up with 300 mL with an alcohol content of 32.5%.
To be conservatively stable, we should try to have an ending alcohol content of 20%. 300 mL of 32.5% alcohol diluted with 187 mL of egg yolks yields an alcohol content of 20%.
The sugar also gets diluted to approx. 101g/L which puts it in port wine territory.
The egg yolks at this point are a firm gel, but if we shear them with the colloid mill we can create a very fluid fluid gel that very much resembles cream.
I’m not sure if I will need to add any ascorbic acid as an anti-oxidant, but I did de-gas the liquid with the chamber vacuum sealer.
This is very thick stuff and really clings to the glass but is so delicious! Thank you aunt Anna for the inspiration.
If anything, this recipe has too much yolk, but I think the ending sugar content is perfect. As it is the liqueur is best used in place of an egg in flip style cocktails or as a coffee creamer. To make it as a stand alone liqueur, I would reduce the yolk quotient and re-adjust the sugar content to keep close to 100 g/L.