Preheat the oven to 300 degrees.
In a medium saucepan, heat the cream, half-and-half and vanilla bean over medium heat just until it comes to a boil. Immediately turn off the heat. Set aside to infuse for 10 minutes. In a large bowl, whisk the egg yolks with the sugar just until combined. Whisking constantly, gradually pour in the hot cream mixture. Strain the mixture into a pitcher to smooth it and to remove the vanilla bean.
Pour the mixture into 4 to 6 ovenproof ramekins and arrange in a hot water bath. Sprinkle the custards with the chocolate shavings. Bake in the center of the oven until almost set but still jiggly in the center, 30 to 40 minutes. (The custard will finish cooking as it cools.) Remove from the water bath and let cool 15 minutes. Tightly cover each ramekin with plastic wrap, making sure the plastic does not touch the surface of the custard. Refrigerate at least 2 hours or until ready to serve. When ready to serve, preheat a broiler to very hot (or fire up your kitchen torch). Uncover the ramekins. To make the sugar coating, pour as much sugar as you can fit onto the top of 1 of the custards. Pour off the remaining sugar onto the next custard. Repeat until all the custards are coated. Discard any remaining sugar. Place the ramekins on a baking sheet and broil until the sugar is melted and well browned, about 2 minutes. Let cool 1 minute before serving.