Preheat oven to 325°F (160°C).

In a heavy-bottomed saucepan, combine butter, allulose, and Swerve.

Cook over medium heat until butter and sweeteners have melted. Allow to come to a boil, stirring constantly, and cook until the sweetener starts to smoke lighty. Do not burn.

Add heavy cream, about half a cup at first. The mixture will bubble violently. After the bubbles slow, add the rest of the cream. Turn off heat.

Add vanilla bean and salt, stir to combine.

In a separate bowl, whisk egg yolks well. Temper the egg yolks by ladeling a thin stream of hot cream mixture into the eggs while whisking continuously.

After ladeling about half the cream mixture into the eggs, transfer the egg mixture into the remaining cream mixture.

Strain the mixture through a sieve, discarding vanilla bean. Pour into 6 4-oz jars or ramekins.

Place ramekins in a 9x9" baking dish, and pour boiling water in dish to come halfway up the sides of the jars.

Tent baking dish loosely with foil.

Carefully transfer into the oven without getting water into the custard. Bake for 25-40 minutes, checking at 25 minutes.

To check for doneness, carefully jiggle the custards. If the custard moves like water, they are not done. Custards are done when they move more like jello.

Remove from the oven, remove foil, and allow to cool to room temperature in the water. Then transfer to the refrigerator to chill for at least an hour.

Serve with a layer of creme fraiche on top of each custard.