Scoop sugar into a small bowl and set to the side. Take the vanilla bean and, using a sharp knife, make a slit down the center of the vanilla bean pod. Carefully use the knife blade to scoop out the seeds. Alternatively, you can use a small spoon to scoop out the seeds. Add the scooped vanilla bean seeds to the bowl of sugar and mix together to combine, infusing the vanilla bean into the sugar.
In a medium saucepan, combine the cream, milk, kosher salt, the scraped vanilla bean pod, and the vanilla bean sugar then bring to a simmer, whisking until the sugar is completely dissolved.
In a separate small bowl, separate the 6 egg yolks from the egg whites. Whisk the egg yolks until smooth.
Slowly whisk in about ¾ cup of the hot cream mixture into the beaten egg yolks in a thin stream to temper the yolks to start the custard. Add the tempered custard back to the saucepan and return it to the stove.
Stir the mixture constantly over medium heat with a heatproof spatula, scraping the bottom as you go, until it thickens into a custard and coats the spatula. If you have an instant-read thermometer, it should read 170-175° F at this point.
Pour the prepared custard through a fine-mesh strainer fitted over a medium bowl. Add vanilla extract and stir until smooth. Let custard cool completely to room temperature.
Refrigerate the custard until very cold, at least 4 hours to overnight. When cold, Pour the custard into an ice cream maker and churn to freeze according to the manufacturer's instructions Store in an airtight container and freeze for a minimum of 2 hours until ready to serve.