Gently warm 1 cup of milk to about 110°F (43°C). Sprinkle 2 teaspoons of active dry yeast over the warm milk and let it sit for 5–10 minutes until frothy.

In a stand mixer bowl, combine 3 cups of all-purpose flour, ½ cup of cocoa powder, ¼ cup of brown sugar, and 1 teaspoon of salt. Mix on low speed until well combined.

Add the activated yeast mixture, 1 beaten egg, and ½ cup of softened unsalted butter to the dry ingredients. Mix on medium speed for about 3 minutes until the dough is soft and slightly sticky.

Transfer the dough into a greased bowl, cover it, and let it rise in a warm place for about 1½ to 2 hours, or until it has doubled in size.

Mix together ¾ cup of brown sugar, ¼ cup of cocoa powder, and 2 teaspoons of ground cinnamon in a medium bowl. Add 1 teaspoon of vanilla extract and stir until it forms a smooth paste.

Turn the risen dough out onto a floured surface and roll it into a large rectangle. Spread softened butter over the surface and evenly sprinkle the filling mixture. Roll the dough tightly into a log and slice into 9–11 even pieces.

Place the sliced rolls in a greased baking dish. Cover and let them rise for another 30–60 minutes.

Preheat the oven to 350°F (180°C) and bake the rolls for about 20 minutes until golden brown.

Whisk together 1 cup of powdered sugar, 2 tablespoons of cocoa powder, and 3 tablespoons of heavy cream until smooth to prepare the glaze.