In a large measuring cup, pour together 2 cups of eggnog and 1 cup of heavy whipping cream. Whisk until fully combined and smooth. Set aside.

In a medium saucepan, combine ¾ cup of granulated sugar, ¼ cup of cornstarch, ¼ teaspoon of salt, and ½ teaspoon of ground nutmeg. Whisk together thoroughly.

Add 4 large egg yolks to the dry mixture and whisk until smooth.

Gradually pour the eggnog and cream mixture into the saucepan while whisking constantly.

Place the saucepan over medium heat, stirring frequently for about 8 to 10 minutes until thickened.

Once thickened, remove from heat and stir in 1 teaspoon of rum extract and 2 tablespoons of unsalted butter until melted and smooth.

Pour the pudding through a fine-mesh sieve into a clean bowl. Cover with plastic wrap directly on the surface. Chill for at least 4 hours or overnight.

Serve the pudding in small cups or shot glasses, topped with whipped cream, grated nutmeg, and optional sugared cranberries.