Once the milk and butter has cooled down enough, add in 1/4 C of sugar, and your yeast, giving it a quick stir, and set this aside for about 15-20 minutes, so your yeast activates.
While you're waiting on your yeast, put you the eggs. remaining 1/2 C sugar, vanilla, and cinnamon, and mix to just combine and beat the eggs.
Add in 3 cups of the flour, and mix to just combine. The dough at this point is going to be very sticky. Add in the additional 1 1/2 cups of flour, 1/2 cup at a time, until it is all mixed in. It is still a sticky dough, so when you turn it out onto a surface to knead it, make sure your surface is well floured.
Once your dough is oiled, cover it with a towel and set it in a warm place to rise, for at least an hour. You'll want it to roughly double in size, if you can. Like I mentioned in my fresh bread post, I like to let my dough's rise in my oven, with the light turned on, but if you have a warm house, leaving it covered on the counter is fine. While you're waiting on your dough to rise, put 3/4 C of the brown sugar in a bowl, with 2 Tbs of cinnamon, and mix together, for the filling.
I let my dough rise for 2 hours, because I got caught up making supper, but this worked out just fine. Once I was ready to roll out the dough, I sprinkled my counter top liberally with more flour, and rolled it out to a rectangle, roughly 10"x14".
Once everything is rolled out (and this dough rolls out very easily), spread your softened butter all over, leaving a 1" lip on the long far side. On the far side of the dough, brush the 1" with water, to help seal the dough after your roll it up.
After your butter is spread out (I just spread it out with my fingers), spread the brown sugar and cinnamon all over it. This brown sugar and cinnamon mixture is just enough to cover everything. Once you have it spread evenly, slowly begin to roll your dough up on itself, trying to keep it as tight a roll as possible. I didn't do anything extreme about it while I was rolling it, I was just trying to keep it a tight, consistent roll.
Once your rolls are, well, rolled up, turn the log over so that the seam is facing up and pinch it shut. I rolled my log around a bit, making sure that the filling was evenly spread, and the layers were tight inside.
Anyway, I cut mine with dental floss, so that the cut is clean, and I don't end up smashing the delicate dough. I scoot the floss under the log, and cross the threads over each other, and pull it. Like tying a knot, without actually tying it. You can tie a knot if you'd like, but its not necessary.
This floss cuts the dough cleanly, without smashing the dough and the layers in between.
Lay each cut roll into a greased 9"x13" pan, cover with plastic wrap, and stick it in the fridge over night!
The next morning, take your rolls out of the fridge, and set them on the counter for 30 minutes, remove the plastic wrap, and preheat your oven to 350*. While you're killing 30 minutes, you may as well make up the icing (if you want any). In a small mixing bowl, put the corn syrup, 2 Tbs of cream (or milk), and vanilla and mix to combine.
Sift your powered sugar, and add to the liquid. This will form a very thick paste, and you can add as much cream or milk to thin it out, as you would like.
I ended up adding in another 3 Tbs of cream, to get this spreadable frosting. Keep in mind that cream is heavier than milk, so if you're using milk, the amounts may very.
Oh my, do these puff up in the oven. These are honestly, sweet enough to not need an icing, but for me, a cinnamon roll just isn't a cinnamon roll without it!