In a medium bowl, whisk the activated charcoal in a bowl with ½ cup of the milk and the heavy cream.
In a separate small bowl, combine 2 tablespoons milk with the corn starch and whisk into a slurry.
In another medium bowl (preferably one with a resealable lid), combine the mascarpone and salt.
Place the first milk mixture in a saucepan with sugar, corn syrup and vanilla. Bring to a boil and boil for 4 minutes.
Remove saucepan from heat and stir in the corn starch slurry. Return mixture to heat and bring to a boil once again, stirring continuously for 1 minute (or until the mixture begins to thicken and coat the back of your spoon.)
Pour saucepan mixture into bowl with mascarpone mixture and stir to combine. Cover and refrigerate a couple of hours (or until cool.)
Once mixture is cold, add to an ice cream maker and churn according to the manufacturer’s directions. Transfer to a resealable container and freeze to finish.
Ice cream will keep for quite some time in the freezer, so feel free to make this recipe in advance!