Step 1

In a large saucepan over medium heat, bring 1/2 cup cream and cocoa powder to a boil, whisking often to blend the cocoa. Reduce the heat and simmer for another 30 seconds, whisking constantly.

Step 2

Remove from the heat and stir in the chocolate until smooth. Stir in the remaining 1/2 cup cream. Pour the mixture into a large bowl, scraping the pan as much as possible. Place a mesh strainer on top of the bowl.

Step 3

In the same saucepan over medium heat (no need to clean it), warm the milk, sugar, and salt.

Step 4

In a separate small bowl, beat the egg yolk. Slowly pour some of the warm milk into the yolk, whisking constantly, then scrape it all back into the saucepan.

Step 5

Continue cooking over medium heat, stirring often, until the mixture thickens and coats the back of a spatula or spoon (170F on a thermometer).

Step 6

Remove from the heat and pour through the mesh strainer into the chocolate mixture. Stir in the vanilla. Place the bowl in an ice bath and cool until room temperature. When cool, refrigerate for at least 1 hour or until cold.

Step 7

While the ice cream base is chilling, make German Chocolate Frosting (get the instructions here).

Step 8

Once the ice cream mixture is cold, freeze it in your ice cream maker according to the manufacturer's instructions. Once it's churned, fold in spoonfuls of the frosting. Freeze in an airtight container until firm, roughly 4 hours or overnight.