Pour the water into a large bowl and whisk in the yeast. Let it sit for 1 minute, then whisk in the brown sugar, butter and salt. Switch to a rubber spatula and start to add in 3 cups flour, 1 cup at a time. Then add in 3/4 cup more, a 1/4 cup at a time until it's all incorporated. At this point, if the dough is still sticky, continue to add flour a 1/4 cup at a time until it is no longer sticky. The dough should bounce back after you poke it when it's ready to knead.