Grease a 10-inch cake pan with cooking spray or butter. Set aside.
In the bowl of a stand mixer, combine warm milk, warm heavy cream, yeast, and sugar. Let sit for 5 minutes or until the yeast has been activated and the mixture is foamy.
Add the egg, salt, and all-purpose flour. Mix until a shaggy dough forms. Knead for 8-10 minutes or until a smooth dough forms. Transfer the dough to a clean bowl, cover, and let rise for 1 hour or until doubled in size.
Meanwhile, prepare the black sesame paste. In a food processor, puree the black sesame seeds until the oils have been released and the seeds become a paste. Add the honey and puree until smooth. Set aside.
Punch down the dough. Lightly dust a clean work counter with flour and divide the dough into 8 portions. Roll out each portion into an 8x6-inch rectangle. Spread 1-2 tbsp of the black sesame paste in an even layer, leaving a ¼ inch border. Roll the dough into a tight log and cut the log in half lengthwise, leaving one end intact. Flip the cut sides so that they are facing up and carefully braid the two ropes. Gather the two ends together to create a knot and baking the roll into the prepared pan. Repeat with the remaining dough.
Loosely cover the black sesame rolls with a clean kitchen towel and let rise for another hour or until doubled in size.
Preheat oven to 350 degrees F.
Whisk together the egg with water. Brush the egg wash on the rolls and bake for 25-30 minutes or until golden brown. Remove from heat and serve warm.