Combine the egg yolks, whole egg, sugar, butter and buttermilk in the bowl of a stand mixer and whisk at medium speed.

As the mixture comes together add half of the flour, along with the yeast, cinnamon and salt and continue whisking until combined. Should look like cake batter.

Remove the whisk attachment and replace it with a dough hook. Add another half of the remaining flour and knead on low speed for 5 minutes. At this point the dough should feel soft and moist. If it is TOO sticky, add a bit more flour (one ounce at a time). Knead on low for another 5 minutes or until the dough clears the sides of the bowl.
( If dough drips off hook , add more flour, does not need to completely unstick from bottom ). Sticky is better than dry.

Turn the dough out onto a lightly floured work surface; and form dough into a smooth ball. Transfer to a large bowl that has been lightly lubed with vegetable oil. Rotate the bowl so that the dough ball is evenly covered. Cover with a plastic wrap and set aside until the dough doubles in volume, about 3 hours.

Assemble:

Butter a 6 by 10-inch ( 2.2 liter ) glass baking dish ( or 8x8 making 5 rolls ) with butter.
Wet counter and cover with a 12x18 inch sheet of plastic wrap.
Scrape dough on to wrap and shape to a 9x12 rectangle. Use rolling pin to even out.
Lightly butter dough leaving border on top edge.
Sprinkle the brown sugar/cinnamon/salt mixture over the dough, also avoiding the top border. Press filling into dough.
Lift plastic wrap to roll dough into 12 inch log, pressing down to form tight cylinder.
Using sharp or serrated knife, cut into 5-6 pieces.
Arrange rolls in baking dish; cover tightly with plastic wrap and store in the refrigerator 8 or up to 24 hours.

Final rise and bake:

Optional: remove rolls from fridge and allow to sit at room temp for hour or two.

Bring 1-2 qts water to boil, place in oven with rolls - let rise one or two hours.
Remove rolls, brush tops with melted butter ( about 1 Tbs ),preheat to 350 degrees.
Bake 20-25 minutes.
Internal temp should be 195-200 degrees. Overbake will make dry rolls.
Check halfway thru and if very brown, cover for remaining time.
Allow rolls to cool for 10 minutes before icing.

Icing:

Soften cream cheese in microwave to 20-45 secs, whisk in melted butter/vanilla, whisk in sugar till smooth. Spread over warm rolls and serve.