In a medium saucepan, combine whole milk, heavy cream, sugar, and salt over medium heat. Stir constantly for about 5 minutes until the sugar has fully dissolved.

In a separate small bowl, mix the instant espresso powder with your strong brewed coffee until fully dissolved.

Carefully pour the dissolved coffee mixture into the saucepan with the warm milk mixture. Stir gently until evenly distributed.

In a separate bowl, whisk the egg yolks until smooth and pale, which should take about 2-3 minutes.

Slowly ladle about a cup of the warm milk mixture into the bowl with the egg yolks while whisking constantly.

Return the saucepan to medium-low heat and cook the mixture for about 8-10 minutes until it thickens.

Once thickened, strain the custard through a fine-mesh sieve into a clean bowl to remove lumps. Allow it to cool at room temperature for about 15 minutes.

Cover the bowl with plastic wrap and refrigerate for at least 4 hours or overnight.

Once fully chilled, pour the custard into your ice cream maker and churn according to the manufacturer's instructions.

Transfer the churned gelato into an airtight container and freeze for at least 4 hours until solid.