In a mixing bowl, combine light brown sugar, black cocoa powder, and ground cinnamon. Stir until fully blended, then set aside.

In a large bowl or stand mixer, combine all-purpose flour, unsweetened cocoa powder, instant dry yeast, fine salt, and instant espresso. Mix thoroughly.

In a saucepan, gently heat whole milk, granulated sugar, and unsalted butter over low heat until warm (approximately 110°F). Stir continuously.

Slowly pour the warm milk mixture into the bowl of dry ingredients while mixing on low speed until a sticky dough forms.

Crack a large egg into the dough mixture and mix on low speed until incorporated.

Cover the bowl with a kitchen towel and let the dough rest at room temperature for 15 minutes.

On a lightly floured surface, roll the dough into a large rectangle. Spread softened butter and sprinkle the chocolate filling mixture across the dough.

Starting from one long side, tightly roll the dough into a log. Cut the log into 9 equal pieces.

Cover the pan with a towel and place it in a turned-off oven for about 30 minutes.

After proofing, preheat your oven to 350°F (175°C). Bake the rolls for 26-32 minutes until golden brown.

In a microwave-safe bowl, combine unsalted butter, chocolate chips, and a splash of milk. Heat until melted, stirring until smooth.

Allow the baked chocolate cinnamon rolls to cool for about 5 minutes, then drizzle the glaze over the rolls.