Separate the 12 egg yolks from the whites. Freeze the whites in a sealable container for later use. In a large bowl, combine the yolks and sugar.
Whisk until they are beyond the point of being merely combined; but have become creamy in texture and pale yellow.
Add whole milk slowly while combining with whisk. Add Bourbon, Cognac, and Dark Rum gradually while stirring. Add heavy cream and salt. Stir slowly until homogenized thoroughly. Transfer to a glass jar and seal tightly. Although you can consume it now, I would recommend waiting at least a week. A month seems to be the perfect aging before serving.
The night before serving, put the egg whites in the fridge to thaw overnight. Make sure they are at room temperature before proceeding to the next step. Place the egg whites in a stand mixer with the whisk attachment. Whisk on high for about 2-3 minutes until stiff peaks form. Remove to a large punch bowl.
Add the 1 1/2 cups of heavy cream to the mixer with whisk attachment and whisk on high until medium peaks form. About 2 minutes.
Stir the previously stored egg yolk and whiskey mixture and then add to the punch bowl with the egg whites. Fold the whipped heavy cream mixture into the punch bowl as well until no pockets remain. Grate fresh nutmeg over the top and serve.