In a large mixing bowl, combine all-purpose flour, unsweetened cocoa powder, instant dry yeast, fine salt, and instant espresso. Whisk these dry ingredients together for about 1 minute until evenly distributed, then set aside.

In a small saucepan, gently warm the whole milk, granulated sugar, and unsalted butter over low heat, stirring until the butter melts. Aim for a temperature of around 110°F, warm but not hot, to help activate the yeast. Pour this warm mixture into the bowl of dry ingredients and mix until it starts to come together.

Crack a large room-temperature egg into the dough mixture and stir until a sticky dough forms. This may take about 2 to 3 minutes of vigorous mixing. If the dough seems too sticky, gradually incorporate a little more flour until it’s workable but not dry. The dough should feel slightly tacky to the touch.

Transfer the sticky dough onto a lightly floured surface and knead for about 5 to 7 minutes. You're aiming for a smooth, elastic texture that springs back when poked. If your fingers stick to the dough, add a little flour at a time to avoid excessive dryness. Once done, place it in a greased bowl, cover it with a damp cloth, and let it rest for 15 minutes.

After resting, roll out the dough on a floured surface into a rectangle about ¼ inch thick. Spread softened unsalted butter generously over the surface.

In a small bowl, mix dark chocolate cinnamon filling ingredients: packed light brown sugar, black cocoa powder, ground cinnamon, and a pinch of salt. Sprinkle this mixture evenly over the buttered dough.

Starting from the longer edge of your rectangle, carefully roll the dough tightly into a log shape. Cut the log into equal pieces, about 1 to 1.5 inches thick.

Place the cut rolls into a greased baking pan, leaving a little space between each. Cover them with foil or a damp towel and let them rise in a warm oven (about 100°F) for 30 minutes.

Preheat your oven to 350°F and bake the chocolate cinnamon rolls for 26 to 32 minutes, or until they are golden brown. Allow them to cool slightly after baking.

While the rolls cool, melt the unsalted butter and chocolate chips in a saucepan over low heat, stirring until smooth. Whisk in powdered sugar and vanilla extract until the glaze is thick and glossy.

Drizzle the luscious chocolate glaze over the warm rolls, allowing it to seep into every crevice. Serve the chocolate cinnamon rolls warm.