• Combine the yeast, warm milk, vanilla extract and sugar in the bowl of a stand mixer fitted with the hook attachment. Allow to sit for 2-5 minutes for the yeast to dissolve. Add in the cocoa powder, 2 cups of the flour and mix to combine. Now add in the salt and egg. Mix well.
• Begin gradually adding in the remaining flour, adding one cup at a time, until the dough begins to pull away from the sides of the bowl. Then, slowly mix in the softened butter, one piece at a time.
• Continue to knead the dough until it is well-developed and can pass the windowpane test. Once done, cover the dough and let it proof until it has doubled in size.
• In a small bowl combine the softened butter, brown sugar, cinnamon, cocoa powder and vanilla extract. Mix well to combine.  Set aside until needed.

Shape the Dough

• Preheat an oven to 350°F and line a 9x13 baking dish with parchment paper.  On a lightly floured surface, roll the dough out into a 10×15-inch rectangle.
• Spread the filling over the dough. Starting with the long end, roll the dough into log. Cut into 12 equal sized rolls, place in prepared dish.  Cover and let proof for 30 minutes or until puffy.

• Place in the preheated oven and bake for 30 minutes. Remove from the oven and cool before icing.
• In a small bowl combine the ingredients for the chocolate icing. Mix well.  Drizzle the icing over the cooled cinnamon rolls.  Enjoy!