In a medium saucepan, combine the heavy cream, whole milk, sugar, vanilla extract, fresh mint leaves, and salt. Heat over medium heat until the mixture is hot but not boiling, stirring occasionally to dissolve the sugar. Remove from heat and let the mint steep for about 30 minutes.

In a separate bowl, whisk the egg yolks until they are pale and slightly thickened. Gradually add about 1 cup of the warm cream mixture to the egg yolks, whisking constantly to temper the eggs.

Pour the egg yolk mixture back into the saucepan with the remaining cream mixture. Cook over medium-low heat, stirring constantly, until the mixture thickens enough to coat the back of a spoon (about 5-7 minutes). Do not let it boil.

Strain the mixture through a fine-mesh sieve into a clean bowl to remove the mint leaves. Cover the bowl with plastic wrap and refrigerate until completely chilled, at least 4 hours or overnight for best results.

Once chilled, churn the mixture in an ice cream maker according to the manufacturer's instructions. If desired, add mini chocolate chips during the last few minutes of churning.

Transfer the ice cream to an airtight container and freeze for at least 4 hours or until firm.