Start with the poolish: In the bowl of a stand mixer fitted with the paddle attachment, combine the milk, yeast, and bread flour for about 1 minute on medium low speed. Scrape down the sides and cover the bowl with plastic wrap. Let sit at room temperature for 1 hour, until doubled in volume.
Moving on to the dough: Scrape the poolish out into another container temporarily, then put the stand mixer bowl back on the machine (no need to clean the bowl). Cream together the butter, sugar, and salt for about 1 minute on medium speed.
Add the eggs one at a time, mixing for about 30 seconds on medium speed each time. The mixture will look very curdled and that's fine.
With the mixer on medium low speed, add 1/4 of the poolish at a time to the bowl, one piece every 30 seconds.
Increase the mixer speed to high and beat until the mixture looks like cake batter, with a light and creamy texture, for about 1 minute.
Turn the speed back down to low, and add the flour. Once incorporated, increase the speed to medium and mix for 3 minutes.
Scrape down the sides of the bowl, then wrap the bowl tightly with plastic wrap. Refrigerate overnight, or for a minimum of 8 hours.
Mix the filling: In a small bowl, stir to combine the brown sugar, cinnamon, and salt.
Remove the dough from the fridge and place on a lightly floured surface. Roll it into a rectangle 7" long and 18" wide.
Brush the entire top surface of the rectangle with the butter, then evenly sprinkle the brown sugar filling all over the top, but leaving a 1/2" empty edge at the top of the rectangle (see picture if necessary). Pat the brown sugar filling gently into the dough to help it stick, but do not smash the dough down.
Roll the dough up tightly from the bottom 18" edge (see picture), then pinch the seam together at the top. Use a knife or bench scraper to cut the log into 12 even pieces (I cut the roll in half, then each in half again, then each quarter piece into 3 pieces). Each roll should be about 1.5" wide.
Line a quarter sheet pan (or a 9x13 casserole dish) with parchment paper, and place all 12 cinnamon rolls in the pan. Gently flatten the rolls with the palm of your hand until they are 1" tall.
Cover the rolls with a lid or with plastic wrap, and let rise at room temperature for 2 hours, during which time the rolls will expand greatly and fill in most of the empty space between.
30 minutes before baking, preheat the oven to 375F.
Remove the lid or plastic wrap, and bake the cinnamon rolls for 15-18 minutes, until the cinnamon rolls are golden brown and risen. If you want to check for doneness with a thermometer, they should be at least 195F.
Make the Icing: While the cinnamon rolls bake, prepare the icing. Using a hand mixer (or even just a sturdy whisk), mix together the butter, confectioner's sugar, orange juice, orange extract, and salt, until smooth and combined.
When the cinnamon rolls have finished baking, let them cool for 3 minutes, then slather on all the icing. It should melt into the crevices of the rolls. Serve and enjoy while warm!