In a small saucepan, bring 1 cup milk and the ground coffee to a boil. Turn off the heat and let sit for 10 minutes to infuse.
In a mixing bowl, whisk together the sugar, cocoa, cornstarch, and salt. In a thin stream, whisk in the remaining milk until smooth. Whisk in the half-and-half until smooth. Whisk in the coffee infused milk, and then pour the mixture through a fine sieve or chinois into a saucepan. Over medium heat, whisking the mixture constantly, bring to a boil and boil gently 2 minutes.
Turn off the heat and stir in the bittersweet chocolate and vanilla extract. Pour the mixture into 1-cup ramekins, cups, or mugs. Refrigerate until well chilled. (The recipe can be made through this step up to 2 days in advance.) Serve cold.
Cinnamon Toasted Soldiers: Preheat oven to 375 degrees F. Combine the sugar and cinnamon. Toss the brioche sticks in the melted butter, then the cinnamon sugar. Place on a sheet pan and bake for 10 minutes, or until crisp and golden brown.