Mix together warm water, buttermilk, sugar, melted butter and yeast in a medium mixing bowl (allowing room in the bowl for yeast to expand). Let sit for 15 minutes.
Add flour, salt, and eggs to a large mixing bowl; stir. Pour yeast mixture on top of flour mixture. Mix for 10 minutes (I prefer to use my Kitchenaid mixer with bread hook- makes it even faster!) and then let the dough sit for about 15-20 minutes (while you clean up your kitchen and prepare the filling).
In a small bowl, mix together melted butter, both sugars and cinnamon; set aside.
On a well-floured service, roll dough into a large rectangle. Spread filling over the entire surface and roll dough up (roll from the long side, like a hot dog).
Slice the cinnamon "log" into 18 rolls and place the rolls carefully onto a lightly greased baking dish (I used an aluminum baking ban for my first dozen and added the last 6 rolls to my favorite cast iron skillet). Cover rolls with plastic wrap and let sit for another 15-20 minutes.
Remove plastic wraps and bake at 375° F for 15-20 minutes.
While your rolls are baking, make frosting (see recipe options below) and spread on warm cinnamon rolls. These are wonderful warm!
Notes
Modified from these one-hour cinnamon rolls on lil' luna
Recipe by Food Fun Family at https://foodfunfamily.com/most-amazing-quick-cinnamon-rolls-ever/