Place the softened butter and sugar in the bowl of a stand mixer fitted with a paddle and mix for 2 minutes on medium/low speed.
In a separate bowl, combine the room-temperature milk and instant yeast. (Give it about 5 minutes for the yeast to foam up, this isn't necessary if you know your yeast is good and alive).
Add the yeast-milk mixture and salt to the whipped butter and sugar. Mix on low until combined (about 2-4 minutes)
Add the flour and mix on low speed for about 2 minutes or until evenly combined.
Remove and scrape the paddle attachment, then replace it with a dough hook attachment. Bring the mixer to medium-low speed (a 2 on my kitchen aid stand mixer) for about 8 minutes until you have a smooth dough. Cover with a damp rag or plastic wrap and allow it to rest in a warm spot for 90 minutes.
In a small bowl combine the brown sugar, cinnamon, and flour. Set aside.
Once the dough has rested and risen significantly, gently pat it down and place it onto a lightly flowered table. Roll it out evenly until it becomes a rectangle measuring 14x24 inches.
Rub the softened vegan butter evenly on the surface of the rolled-out dough, making sure to leave ½ an inch of the dough blank at one of the long (24-inch) ends.
Evenly sprinkle the brown sugar cinnamon mixture over the buttered dough, and gently rub the sugar mixture into the butter.
Preheat the oven to 350℉
To roll, start on the 24-inch side that isn't blank, and tightly roll toward the blank side. Position the roll seam side down. (You can also lightly dampen the plain end of the dough with water and a pastry brush before rolling to help seal the roll).
You will more than likely need to trim a little off the ends of the roll for consistency. Now cut the roll into 12 even rolls, each about 2 inches.
Line a 13x9-inch Pyrex pan with parchment paper. Load the pan with the rolls lined 3x4. Cover with plastic wrap and set in a warm place for 30-60 minutes.
Once the oven has preheated and the rolls have risen, remove the plastic wrap and place the cinnamon rolls in the oven for 20-25 minutes. Once done, remove from the oven to cool. (don't forget to turn off the oven!)