01 - In a medium saucepan, whisk together cocoa powder, sugar, and salt. Stir in milk and heat over medium, stirring constantly until warm and sugar dissolves.
02 - Add chopped dark chocolate, stirring until fully melted and smooth.
03 - In a separate bowl, whisk egg yolks. Gradually pour about 1 cup of the warm chocolate mixture into the yolks, whisking constantly to temper.
04 - Return yolk mixture to saucepan with remaining chocolate mixture. Cook over low heat, stirring constantly with wooden spoon, until mixture thickens and coats the back of the spoon without boiling.
05 - Remove from heat and stir in heavy cream and vanilla extract.
06 - Strain mixture through a fine-mesh sieve into a clean bowl. Allow to cool to room temperature.
07 - Cover and refrigerate for at least 4 hours until thoroughly chilled.
08 - Churn mixture in an ice cream maker following manufacturer’s instructions.
09 - Transfer churned ice cream to a lidded container and freeze for at least 2 hours until firm.