In a large saucepot over medium heat, combine heavy cream, whole milk, and light corn syrup and stir constantly until it almost comes to a boil. In the meantime, add egg yolks and granulated sugar in a large bowl. Mix until well combined and lightened in color. Temper these eggs by adding the liquid into the egg yolk mixture in four equal intervals, while constantly whisking to prevent the egg from coagulating. Return mixture to the saucepot and heat over low heat until 175°F (80°C) or “nappe”. Nappe is when you take a wooden spoon, immerse it in the custard, and turn it over with the back of the wooden spoon facing you. Run your index finger down the spoon. If you end up with a clean line down the middle, your ice cream base is ready. Remove from heat and strain the mixture through a fine strainer. Add vanilla extract and pistachio paste and stir until the pistachio paste has dissolved into the ice cream base. Using an ice bath, chill the ice cream base completely and refrigerate for at least four hours or up to one day. Pour the chilled mixture into an ice cream maker and freeze according to the manufacturer’s directions. Remember to review the capacity of your machine. When the ice cream is churned, place it into a chilled storage container. Fold in chopped pistachios. Store in the freezer. 

Pro Tip:

If pistachio paste is unavailable commercially, the following instructions will result in a bright green pistachio paste. What makes the best pistachio paste? Raw pistachios that are unsalted and not roasted. To remove any brown skin of the pistachios you need to blanch them. 

Bring a pot of water to a boil, add the pistachios, and remove the pot from the heat. Soak the pistachios for 30 seconds and then transfer them into a bowl with ice water. Transfer the cooled pistachios to a clean towel. Gently rub the blanched pistachios between the towels to peel off any brown skin. You may need to help some stubborn ones by peeling them individually with your fingers. Separate the peeled pistachios from the brown skin. This process can be a bit tedious, but it is worth it. Add the pistachios to a food processor. Process until smooth, adding as little water as possible to smooth things. During this process pistachios go through different stages: whole > crumbs > powder/flour > paste.