In a medium bowl, combine 1 cup of brown sugar, ½ cup of black cocoa powder, and 1 tablespoon of ground cinnamon. Stir until well mixed, ensuring there are no lumps.

In a large mixing bowl, whisk together 4 cups of all-purpose flour, ¼ cup of unsweetened cocoa powder, 2 teaspoons of instant dry yeast, 1 tablespoon of instant espresso (if desired), and 1 teaspoon of fine salt. In a separate saucepan, gently warm 1 cup of whole milk, ½ cup of granulated sugar, and ½ cup of unsalted butter over low heat until the butter melts. Pour the warm mixture into the dry ingredients to form a dough.

Add 1 large egg to the dough mixture and knead for about 5 to 7 minutes until the dough becomes smooth and elastic. Cover the bowl with a clean kitchen towel and let it rest for 15 minutes.

On a floured surface, roll the dough into a large rectangle (12x18 inches). Spread ¼ cup of softened butter over the dough, sprinkle the filling mixture on top, roll tightly, and cut into 12 equal pieces.

Place the sliced rolls in a greased baking pan and cover with a towel. Let them rise in a warm place for about 30 minutes or until doubled in size.

Preheat your oven to 350°F (175°C). Bake for 26 to 32 minutes until golden brown and edges are slightly crisp.

In a saucepan, combine ½ cup of unsalted butter, 1 cup of chocolate chips, and ¼ cup of whole milk. Stir until smooth, then whisk in 1 cup of powdered sugar and 1 teaspoon of vanilla extract.

Once the rolls are out of the oven, drizzle the chocolate glaze generously over the top. Allow to set slightly before serving warm.