Separate the eggs yolks from the eggs whites. Whisk the egg yolks in a large bowl - while slowly adding in 1/2 cup sugar - until completely smooth and lightly colored.
Add in the milk heavy cream, bourbon, spiced rum, and 1/2 teaspoon cayenne pepper powder. Lightly stir.
Beat the egg whites with the remaining 1/4 cup sugar, until the egg white mixture thickens and reaches the soft peak stage.
Slowly pour the egg white mix into the heavy cream mix, folding the egg white mix gently until combined.
Mix the grated nutmeg, cinnamon, and remaining 1/2 teaspoon cayenne powder.
Ladle a glass of eggnog, then sprinkle a pinch of the nutmeg/cayenne powder on top.
Notes
Control the heat by adding more (or removing completely) the cayenne pepper powder in the eggnog itself, keeping only the cayenne in the sprinkling powder.