In a large mixing bowl, combine 3 cups of flour, cocoa powder, sugar, baking powder, and salt. Using a whisk, mix until well blended, and form a well in the center.

In a separate bowl, whisk together the milk, melted butter, and eggs. Pour this mix into the well of the dry ingredients. Stir until just combined, using your hands if necessary to form a shaggy dough.

Transfer the dough onto a floured surface and knead gently for about 2-3 minutes, adding the remaining flour as needed until the dough is smooth but still slightly tacky.

Roll the dough into a rectangle about ¼ inch thick. Brush the surface with melted butter, and sprinkle generously with cinnamon.

Starting at one end, tightly roll the dough into a log. Use a sharp knife to slice the log into 12 even pieces.

Place the rolls in a greased baking dish, allowing some space between each roll for expanding. Cover with a clean kitchen towel and let rise in a warm place for 15-20 minutes.

Preheat your oven to 375°F (190°C) and bake for 20-25 minutes, or until the rolls are puffed and set, lightly gilded on top. Allow them to cool slightly before drizzling with frosting.