Step 1

Set aside 1/2 cup of the whole milk.

Step 2

To a medium saucepan, over medium heat, add remaining 3 1/2 cups of milk, salt, cocoa powder, and sugar. Stir to combine and bring to a simmer, stirring constantly.

Step 3

Add the dark chocolate and stir until melted.

Step 4

To the reserved ½ cup milk, add cornstarch and stir until fully dissolved.

Step 5

With the chocolate mixture still simmering, whisk in the cornstarch slurry. Continue cooking, stirring constantly for 1-2 minutes, until the mixture thickens.

Step 6

Remove from heat, stir in vanilla extract, and serve immediately. Refrigerate leftovers in an airtight container for up to 4 days.