Preheat the oven to 325 degrees F. Arrange six 4-ounce ramekins in a deep baking dish.
Split the vanilla bean and scrape the seeds into a saucepan. Add the pod, coconut cream, and oat cream, then heat until steaming but not boiling.
Whisk the egg yolks, granulated sugar, and salt until smooth. Slowly pour in the hot cream while whisking constantly, then stir in the vanilla extract.
Strain the custard into a pitcher and divide it among the ramekins. Pour hot water into the baking dish until it reaches halfway up the sides of the ramekins.
Bake for 30 to 36 minutes, until the edges are set but the centers still wobble gently. Remove the ramekins from the water and cool to room temperature.
Refrigerate the custards uncovered for at least 4 hours. Blot away any moisture from the surfaces and sprinkle each custard evenly with 1 teaspoon turbinado sugar.
Place the ramekins under a preheated broiler for 1 to 2 minutes, watching continuously, until the sugar melts and caramelizes. Chill for 10 minutes so the custard firms again while the topping stays crisp.
