Step 1

Set a medium bowl in a large bowl of ice water. In another medium bowl, whisk the egg yolks until pale and slightly thickened, about 2 minutes.

Step 2

In a spice grinder, pulse the coffee beans until coarsely chopped. In a medium saucepan, combine the coffee with the cream, half-and-half, sugar and salt. Bring to a simmer and cook over moderate heat, whisking occasionally, until the sugar is completely dissolved and the cream mixture is steaming, about 7 minutes. Very gradually whisk half of the hot cream mixture into the beaten egg yolks in a thin stream, then whisk this mixture into the saucepan. Cook over moderately low heat, stirring constantly with a rubber spatula, until the custard is thick enough to lightly coat the back of the spoon, about 7 minutes; don’t let it boil.

Step 3

Transfer the custard to the bowl set in the ice water, stir in the vanilla and let cool for about 30 minutes, stirring occasionally. Pour the custard through a fine-mesh strainer into another medium bowl and refrigerate until very cold, about 1 hour.

Step 4

Whisk the chilled custard a few times, then scrape it into an ice cream maker. Freeze according to the manufacturer’s instructions. Transfer the ice cream to a plastic container, cover and freeze until firm, at least 3 hours.