Preheat the oven to 320°F (160°C). Place 6 baking dishes in a large roasting pan. Bring a pot of water to a boil.
In a medium saucepan, combine cream and 3 tbsp of erythritol.
Split vanilla bean lengthwise. Scrape its seeds into the saucepan, then add the pod. Heat gently on medium temperature just until the mixture starts to bubble a little (around 7 minutes).
In the meantime, whisk the egg yolks with remaining erythritol and salt. Use a large mixing bowl and an electric mixer. Mix until the mixture gets pale yellow.
Start adding the hot cream mixture into the yolk mixture. It might be best to use ladle. You want to prevent the eggs from curdling, that’s why you need add only a small amount of cream at first, and whisk to combine. Next, add two ladles of cream mixture, one at a time, and whisk after each addition. Continue in the same manner, until you mix in all the remaining cream mixture.
Strain through a fine sieve into a large cup. You want to get rid of the vanilla pod and any bits of cooked egg, but try to force the vanilla seeds through the sieve.
Pour custard into baking dishes. Place the roasting pan in the oven.
Pour enough boiling water in the pan to come halfway up the sides of the dishes.
Bake until custards are set (around 35 minutes). When shaken, they should tremble slightly in the middle. Don’t let them get too firm.
Remove dishes from hot water and let them cool on a wired rack for up to 30 minutes. Then, cover them with a foil and place them in the fridge for at least 2 hours (overnight is best).
Before serving, sprinkle about ½ tbsp of powdered erythritol over each creme brulee. Use a blow torch to caramelise it. Erythritol will not caramelise as well as sugar, but it will do the job well enough to offer a similarly crispy experience.
If you don’t own a torch, you can use a broiler, but watch really closely for when the topping is melted. It is advised that you put the creme brulees in a freezer for 15 minutes prior to caramelising, to make sure the custards remain cold after “bruleeing.”
Let the creme brulee sit for a couple of minutes before serving. Enjoy every bit of it!