1-First, warm the 2 cups half and half, granulated sugar, and 1/4 teaspoon fine sea salt in a medium saucepan over medium heat, whisking to dissolve the sugar. Then, beat the 4 egg yolks in a bowl and add 1/2 cup of the warm mixture to the yolks, whisking to combine. Next, add the egg yolk mixture back to the saucepan with the remaining half and half mixture.

2-Whisk and Cook the Base: Whisk in 1 to 1 1/2 tablespoons instant coffee granules until fully dissolved, then cook over medium-low heat, stirring constantly until the custard thickens and coats the back of a spatula or reaches 170 degrees Fahrenheit. Place the second 1 cup of heavy cream in a bowl with a fine mesh strainer over it, and strain the hot custard through the strainer into the cream, discarding any solids.

3-Stir in 1 teaspoon pure vanilla extract, then transfer the mixture to an airtight container and chill it completely in the refrigerator, preferably overnight. For the next part, pour the chilled mixture into an ice cream maker and churn for 30 to 40 minutes until frozen. Finally, transfer the churned ice cream to an airtight container and freeze for about 4 hours until fully set.