Whisk egg yolks and 1 tablespoon sugar together in a bowl until sugar is dissolved. Whisk in eggnog, cream, and vanilla extract until thoroughly combined.
Pour eggnog mixture into 4 ramekins. Place ramekins in baking dish; pour in enough boiling water to come half way up the sides of ramekins.
Bake in the preheated oven until set, about 1 hour. Cool slightly, cover ramekins with plastic wrap, and refrigerate at least 4 hours.
Set oven rack about 6 inches from the heat source and preheat the oven's broiler.
Remove plastic wrap from ramekins. Sprinkle 1 tablespoon of sugar in a thin layer over top of each ramekin. Brown the sugar using a kitchen torch or under a broiler until golden and caramelized, 30 seconds to 1 minute.