In a medium saucepan, combine heavy cream, whole milk, and half of the sugar. Heat over medium heat until steaming but not boiling. Stir in the instant espresso powder and a pinch of salt. Remove from heat.

In a separate bowl, whisk the egg yolks with the remaining sugar until the mixture becomes pale and slightly thick.

Slowly pour a ladleful of the hot milk mixture into the egg yolks, whisking constantly. Repeat this process with another ladleful, then gradually pour the egg mixture back into the saucepan.

Return the saucepan to low heat, stirring constantly with a spatula until the mixture thickens and coats the back of a spoon (about 170-175°F). Do not boil.

Pour the custard through a fine-mesh sieve into a clean bowl. Stir in the vanilla extract. Cover and refrigerate for at least 4 hours (or overnight) until thoroughly chilled.

Pour the chilled custard into an ice cream maker and churn according to the manufacturer’s instructions (typically 20-25 minutes). If you don’t have an ice cream maker, freeze in a shallow dish and stir every 30 minutes until firm.

Transfer the churned ice cream to a freezer-safe container and freeze for at least 2 hours before serving.