In a medium saucepan over low to medium heat add the heavy cream, whole milk, sugar and salt. Whisk to fully dissolve the sugar ~ 4 to 5 minutes.
In a large glass bowl add the egg yolks. Whisk the yolks together.
Whisk 1 cup of the hot milk mixture into the egg yolks while whisking the milk mixture until fully combined.
Add the egg yolk mixture to the saucepan. Whisk until it comes to a simmer.
Remove the saucepan from the heat and mix in the vanilla and espresso.
Pour the mixture through a sieve and place in fridge until chilled (about 6 hours, but leave it overnight in the fridge to make it easy).
Add mixture to ice cream maker and churn for 20-25 min.
Freeze mixture for another 3 hours until fully chilled for ice cream and not just soft serve.