01 - Combine the milk, 1 cup of the heavy cream, sugar, and salt in a medium saucepan. Heat over medium heat, stirring occasionally, until the mixture is steaming but not boiling.
02 - Remove the saucepan from heat and add the fresh mint leaves. Cover and let the mixture steep for 1 hour to extract maximum mint flavor.
03 - Pour the mixture through a fine-mesh sieve to remove the mint leaves, pressing firmly to extract all the flavorful liquid. Return the strained milk mixture to the saucepan and reheat slightly if needed.
04 - Whisk the egg yolks in a medium bowl until smooth. Gradually pour about 1 cup of the warm milk mixture into the yolks while whisking constantly to prevent curdling.
05 - Return the tempered egg mixture to the saucepan. Cook over medium-low heat, stirring constantly with a heatproof spatula or wooden spoon, until the custard thickens and coats the back of a spoon (170–175°F). Do not let the mixture boil.
06 - Remove from heat immediately. Stir in the remaining 1 cup heavy cream, vanilla extract, and green food coloring if using.
07 - Pour the custard through a fine-mesh sieve into a clean bowl. Let cool to room temperature, then cover with plastic wrap pressed directly onto the surface. Refrigerate until thoroughly chilled, at least 4 hours or overnight.
08 - Pour the chilled custard into an ice cream maker and churn according to the manufacturer's instructions. During the last minute of churning, add the chopped chocolate or mini chips and churn just until evenly distributed.
09 - Transfer the churned ice cream to an airtight container, pressing a piece of parchment paper against the surface to prevent ice crystals. Freeze until firm, at least 2 hours.
10 - Let the ice cream sit at room temperature for 5 minutes before scooping to achieve the optimal creamy texture.