Pour the milk into a pot, add half the sugar and the mint leaves. You don't need to take the mint stems. While stirring, slowly heat the milk, being careful not to bring it to a boil.
Remove the pot from the stove and leave for at least 1 hour to allow the milk to soak in the mint flavor. Then strain the milk through a sieve and squeeze out the mint. You don't need it anymore. Heat the milk again, without bringing it to a boil.
Whisk the egg yolks with the remaining sugar. Add hot milk in a thin stream without stopping. Put the mass on a low heat and stir with a spatula until it slightly thickens, without bringing it to a boil. Run your finger over the spatula: if a distinct groove is left, remove the pan from the heat.
Place the pan in a bowl of ice-cold water and cool completely, stirring. With a mixer, whisk the cold cream until creamy and mix with the milk mixture.
Add grated or finely chopped chocolate to the mixture and mix. You can sprinkle the chocolate on the ice cream you have already made.
Put the mass into a wide dish, cover with a lid or cling film, and put it in the freezer for 4-5 hours. Stir the ice cream about every hour to make it homogeneous.
How to make mint ice cream with chocolate at home