While the dough rests, add butter, brown sugar, cocoa powder, and cinnamon to a medium bowl and mix until fully combined. You can do this with a standing mixer, hand mixer, or by hand with a wooden spoon if your butter is soft enough.
After the dough has risen for 1 hour, transfer it to a lightly floured counter top. Use a rolling pin to roll it into a rectangle, around 10 inches wide by 14 inches long.
Use an offset spatula to spread the filling over the dough, covering it entirely aside from a ½ inch on each of the two shorter sides. Sprinkle the chocolate chips over top of the filling.
Starting on the long end, roll the dough into a log. Cut off ½-1 inch of dough from each end and discard. Make sure the seam side is down, then use un-flavored dental floss (or a serrated knife, but this will flatten the rolls a little) to cut the log into 9 even rolls.
Transfer the rolls to a 9 inch round baking dish. Cover with a tea towel or plastic wrap and allow to rise for 30 minutes in a warm place.
With about 10 minutes left in the rising time, preheat the oven to 350℉ or 180℃.
When the rolls have risen for 30 minutes, pour ⅓ cup of heavy cream (or oat milk if making these dairy free) over top of them and bake for 20-27 minutes. If you gently push your finger into the middle of one of the rolls, it should spring back when they're ready. This takes 25 minutes in my oven.