3ouncesbittersweet or semisweet chocolate, finely chopped
Set a fine mesh strainer over a medium sized bowl and set the bowl over a large container of ice water.
In a medium saucepan over medium heat, heat the cream, milk, 3/4 cup sugar, and salt stirring occasionally, until steam appears and the liquid is hot (175 degrees) about 5 minutes.
While the milk mixture is warming, in a separate bowl, whisk the yolks and 1/4 cup of sugar together until smooth. Slowly whisk about 1 cup of the hot milk mixture into the yolks to temper them. Then slowly whisk the tempered yolk mixture back into the remaining hot milk mixture. Continue to cook the custard mixture over medium heat until it is very hot but not simmering (180-185 degrees).
Pour the custard mixture into the strainer bowl set in the ice bath and let cool, stirring occasionally, for about 10 minutes. Remove the custard mixture from the ice bath, cover tightly with plastic wrap and refrigerate until very cold (40 degrees), about 3 hours.
A few minutes before you plan to churn the ice cream, place chocolate in a medium heatproof bowl. Set bowl over saucepan containing barely simmering water; heat mixture until chocolate is melted and whisk until smooth. Stir in oil and transfer to a ziploc bag; set aside.
Pour the mixture into the ice cream canister and churn following the manufacturer’s instructions until the mixture resembles the consistency of thick whipped cream. Snip the corner of the ziploc bag that the chocolate is in, and while the machine is running, slowly drizzle the chocolate into the ice cream. After chocolate is added, continue churning until the mixture resembles soft served ice cream.
Transfer the ice cream to an airtight container. Cover the container and freeze the ice cream until it is firm, about 3 hours.