Nobody should be buying eggnog, especially for themselves. It takes only a couple of minutes to have a great fresh version made.
(note to reader: post goes from simple+great to complex, intensive, pretentious, but terrific. be forewarned)
Easy, Individual Egg Nog
(I do this by feel, so cream etc. is imprecise)
large shaker, chilled
1 egg
Ice (just enough to break up egg during shake)
Heavy Cream or, if desperate, Half&Half; if suicidal, double cream
dry whiskey/scotch
dark rum
maple syrup
nutmeg
--> crack whole egg in chilled shaker; top with ice (4-5), measure of scotch, ~tablespoon of dark rum, half measure of maple syrup or to taste, add cream (say, 2.5oz?). shake hard+strain. pour +garnish with nutmeg. (you should feel comfortable with little guidance on exact measurements. also, a "measure" is about one ounce).
- The quality/freshness of the egg and of the heavy cream are really the major contributors for taste here. Don't store them long or with the other stuff in your freezer -- an egg shell is porous and takes on the flavors of the scents around it, including that airplane-esque smell; heavy cream is just as susceptible, more so than regular milk because of the fat content.
- Buy grade B syrup: it's cheaper, darker, and more flavorful. Fresh nutmeg is great because it's so amazingly aromatic, but most people never smell it and are really just looking for the token of it on top. It's the balanced vanilla flavor of the maple syrup that gets their attention.
- I like scotch (not bourbon, maybe rye) as the main liquor w/ a backup of dark rum for tradition and color's sake. This is because: bourbon is too chewy+sweet to share with maple syrup; cheap scotch is readily available, at quality, and gives structure; brandies, etc, while great and more historically accurate, well made, are much more dear to me.
I'd suggest you make one without maple syrup first to get an idea of what it is you're drinking, which is basically an adult milk shake with little depth; the maple syrup should be enough to bring out the flavors of the drink without making it just a sugar-bomb.
If you want to "improve" it a bit, take it easy with the maple syrup and use some amarula, add healthy pinch ceylon cinnamon to shaker --> darker color, more even taste. (ceylon kicks cassia's ass). grated citrus rind or orange blossom water is also a cheap, effective aromatic garnish suitable for egg nog.
**"Individual" servings take about a minute to make once you get your process down, and from a large shaker to petite glasses, should cater more than enough for two servings**... so you don't really need to do a large batch, for which you would have to be much more precise. I recently served a group of twenty at my house this way, and all I had to do was disappear for a little more than eight minutes with my ingredients, shaker, and two chilled pitchers over ice to transfer successive batches to.
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If you really want to be fancy though, keep these in mind:
- while the health risks from fresh raw eggs of this fashion are really minimal, careful heating over a double boiler will increase the density of your drink and give it a pleasing texture more like the carageenan concoctions of the supermarket. At this point you've made a drinkable custard, but that's nothing to be sorry for; they're damned good. This is difficult, but if you temper-cook the whites (with a cream, etc.) the protein will be more available; conversely, by tempering the yolk you oxidize the cholesterol and thereby cause it to be more harmful.
- if you're really into this, and know something about cooking, the consistency of the best custards comes from carefully separating the whites + yolks; straining off the chalaza/chelate, set aside whites in metal bowl, cover with half-damp cloth and chill; cream the yolks separately in glass bowl with a tinytiny bit of salt and slightly more sugar... infuse the heavy cream and increase its consistency at the same time by taking a flavoring agent (split+scraped vanilla bean), adding it to the cream, and scorching the cream briefly before letting it cool; when still slightly warm, add some of this cream to the yolks, temper whisk high over simmering double boiler, gradually increasing the addition of the cream as it continues to cool...
chill the yolk mixture, adding your liquor and some of the syrup (can't take sugar back once in, so hold off til you taste), let sit for a while to rest.
When ready to serve: stir yolk mixture lightly to incorporate; bring strained whites to soft peaks, setting aside some of egg white meringue for garnish; fold yolk-cream with soft peak egg whites, gently pour into chilled coupe or similar (~3-4oz) and grate nutmeg and citrus rind for garnish. gently add few drops of maple syrup to float atop. Add sugar to remaining egg whites, whip to semi-stiff peak, and spoon to grace top of cup. Use toothpick to draw out figures.
NB: this version, because tempered eggs and no ice added, will be amazingly rich and you should reduce use of sugars accordingly. Also, if you want to cheat for body, you can use a *tiny* bit of cream of tartar or arrowroot. And citrus rind is a terrific compliment for this drink. You'll also note, with the bioavailability comment above about cooked egg whites = better protein, "cooked" yolks = deadly cholesterol, that this is the least healthy version... A double boiler is just a pot of boiling water and a second bowl resting atop without touching the water or the sides -- it's used for careful tempering of eggs, chocolate, etc.
Final mention is the possibility of a small ruby port float, which can be heavenly. If do this, use a brandy for liquor and garnish with star anise.