1. In the work bowl of a standing mixer fitted with the whisk attachment, whip the egg yolks on medium speed until light, about 2 minutes. With the machine on low, slowly add the confectioners’ sugar, and mix until blended. (No need to sift the sugar.) Add the salt and cognac, whisk to blend, and use a rubber spatula to scrape any sugar off the insides of the bowl, whisking on low and scraping until the sugar is totally absorbed into the liquid. Add the rum and 1 quart of the half and half (the liquid should come up almost to the top of the whisk), mix to blend, and transfer to a large mixing bowl. Clean and dry the bowl and the whisk.

2. Next, whisk 6 egg whites until thick and opaque but still soft (soft peak). Add the remaining 2 quarts cream, and whip again to mix. Transfer half of this mixture to each of 2 gallon-sized vessels. (I store my eggnog in 2 ceramic crocks with lids that seal closed.) There will be about 6 cups in each, including the foam.

3. Finally, stir the reserved mixture with the alcohol in it, and divide it between the 2 crocks, again about 6 cups into each. Stir to blend, and refrigerate for about 1 month, stirring (and tasting!) the eggnog once every few days, and ladling liquid from one crock to another, if you’d like the two crocks to taste identical.

4. To serve, whip 6 additional egg whites to soft peaks, and fold into the eggnog. Serve cold, dusted with freshly grated nutmeg.