Preheat oven to 350 degrees F. Place 5 ramekins/custard cups into a shallow baking sheet, and fill the dish with water to half-way up the sides of the ramekins.

Pour the eggnog into a saucepan over medium heat. Cook and stir occasionally until the mixture simmers, about 10 minutes.

Place the 5 egg yolks and sugar into a mixing bowl; beat until light colored. Mix in the mascarpone until well blended and smooth. Whisk 1/3 cup of the heated eggnog mixture into the eggs. Gradually whisk the remaining eggnog into the eggs. Stir in the nutmeg, cinnamon, and vanilla bean paste. Pour into the prepared ramekins, dividing evenly.

Bake until custard has set, 30 to 45 minutes. Centers should wiggle slightly when shaken, but not be soupy. Let cool 30 minutes; refrigerate at least 3 hours before serving.

To serve, sprinkle top with fine bakers sugar and torch with a Crème Brûlée torch until sugar browns and turns to a hard candy consistency. Serve and enjoy!