Step 1: Heat the Cream Mixture : In a medium saucepan, combine the milk, heavy cream, and half of the sugar. Warm over medium heat until the mixture is hot but not boiling. If using fresh mint leaves, add them to the warm mixture, cover, and let steep for 30 minutes. Then strain and discard the leaves.

Step 2: Prepare the Custard Base : In a separate bowl, whisk the egg yolks with the remaining sugar until pale and thick. Slowly pour a little of the hot milk mixture into the yolks, whisking constantly to temper them. Gradually return the mixture to the saucepan. Cook over low heat, stirring constantly with a wooden spoon, until the custard thickens slightly and coats the back of the spoon (170–175°F / 77–80°C).

Step 3: Add Flavor and Chill : Remove from heat. Stir in peppermint extract and salt (and food coloring if desired). Strain the mixture through a fine-mesh sieve into a clean bowl. Cover and refrigerate for at least 4 hours or until completely cold.

Step 4: Churn the Ice Cream : Pour the chilled custard into your ice cream maker and churn according to manufacturer’s instructions (usually 20–25 minutes). During the last few minutes, drizzle in the melted dark chocolate while churning — it will harden into fine, delicate chocolate flakes. (If you don’t have an ice cream maker, freeze the base in a shallow dish, stirring every 30 minutes for 3–4 hours to break up ice crystals.)

Step 5: Freeze Until Firm : Transfer the churned ice cream to an airtight container. Freeze for at least 2–3 hours to set before serving.