Adapted from The Perfect Scoop by David Lebovitz
2 & 1/4 cups heavy cream
6 tablespoons cocoa powder
1 cup sugar
6 ounces unsweetened chocolate, chopped
1 cup whole milk
1 teaspoon vanilla extract
Whisk cream, cocoa powder, sugar, and salt in a large saucepan.
Heat mixture, whisking frequently until it comes to a rolling boil (will be foamy).
Remove from heat and whisk again until chocolate is completely melted, then whisk in milk and vanilla.
Pour mixture into a blender or use an immersion blender for 30 seconds until smooth.
Chill thoroughly in refrigerator (8-12 hours) and then freeze in your ice cream maker.