Adapted from David Lebovitz
2 1/4 cups heavy cream
6 tablespoons Dutch process cocoa powder
1 cup sugar
Pinch of salt
6 ounces unsweetened chocolate, chopped
1 cup whole milk
1 teaspoon vanilla
Combine cream, cocoa, sugar and salt in large saucepan. Heat while whisking till the mixture comes to a boil. Remove from heat and add the chocolate, whisking till melted, then add milk and vanilla. David recommends pouring the mixture into a blender and processing for about 30 seconds to make sure no unmelted chocolate particles remain.
Chill in refrigerator overnight or till very cold. Freeze using ice cream maker, following manufacturers instructions.