Preheat oven to 350˚F.  Line all of the walnuts in a single layer on a small baking sheet.  Toast in the oven for 5 minutes and then let cool.

Using a medium saucepan, heat the milk, sugar, half of the black walnuts, salt and ½ cup of the cream until warm. Cover, remove from heat and let steep at room temperature for 1 hour.

Pour the remaining 1 cup of the cream into a large bowl; set aside. Whisk together the egg yolks in a separate medium bowl; set aside.

Rewarm the mixture then slowly pour into the egg yolks, whisking constantly. Scrape back into the saucepan.

Heat over medium heat while stirring constantly with a heatproof spatula, until the mixture thickens (about 5-7 minutes). Pour the custard into the 1 cup cream through a mesh strainer and stir. Press on the walnuts to extract as much of the walnut flavor as possible, then discard them.  Mix in the vanilla and stir over an ice bath until cool.

Chill the mixture overnight in the refrigerator, then freeze in your ice cream maker according to the manufacturer’s directions.  After transferring the ice cream from the maker to the container, stir in the remaining black walnuts.  Freeze until ready to consume.