Step 1

In a medium saucepan, combine the cream, vanilla pod and scrapings, sugar and salt. Bring to a bare simmer over medium heat, stirring frequently to dissolve the sugar. Cover and steep 20 minutes.

Step 2

Meanwhile, place the egg yolks in a medium bowl and set the bowl on a damp kitchen towel. Measure out the buttermilk and have it by the stove.

Step 3

When the cream has steeped, drizzle it slowly into the egg yolks, whisking constantly. Return the mixture to the pot and cook over a low flame, stirring constantly with a heat-proof silicone spatula, until the mixture thickens slightly, begins to "stick" (form a film othe bottom of the pan, and/or registers 170ºF on an instant read thermometer. Immediately stir in the buttermilk to stop the cooking, then strain the mixture through a mesh sieve and into a bowl or jar. Cover and chill the mixture until very cold, at least 4 hours and up to 2 days.

Step 4

Churn the mixture in an ice cream maker according to the manufacturer's instructions, then scrape into a container and freeze until firm, at least 2 hours. The ice cream is creamiest within the first week of churning, but it will keep in the freezer for up to a month or two. Store it airtight with a piece of parchment paper pressed directly to the surface to prevent ice crystals from forming.