In a pot, combine the whipping cream, eggnog, and half and half. Slowly bring to a boil. Once it comes to a boil, remove from heat.
In a bowl, whisk the egg yolks and 1/4 cup sugar together. Add the vanilla. Whisk until the egg yolks are pale yellow, about 2 minutes.
Add a 1/4 C of the milk mixture to the eggs, slowly, all the while whisking (temper the eggs). Very slowly, add this mixture back to the milk in the pot while whisking the entire time. Whisk until well combined.
Pour equal amounts into four ramekins and place ramekins in a shallow baking dish.
Pour the boiling water into the baking dish, around the ramekins. Keep pouring until the water reaches halfway up the sides of the ramekins.
Bake until the center is slightly giggly still (about 40 - 45 minutes). Remove from oven and refrigerate until set (a few hours).
For the Sugar Crust
Turn the oven to broil and measure out 1/2 cup of sugar.
Spoon some of the sugar onto the top of one of the brulees. Tilt the ramekin to spread the sugar all over the top, and then pour the excess sugar into the next ramekin and repeat the process. Add extra sugar if you need it to cover all.
Place the ramekins in a baking dish and set them very close to the broiler. Watch these constantly as they will burn in a flash if you don’t.
When the sugar has melted and begins to turn a dark amber, remove from the oven and let cool slightly. Serve with a dollop of whipped cream (optional).