Place the flour in the bowl of a stand mixer and pour in the salt and yeast on opposite sides of the bowl, then stir in each one with your finger.  Stir in the sugar with the paddle attachment and add the softened butter, sour cream, and eggs.

Start mixing the dough on low speed and gradually trickle in the warm milk.  Add just enough milk to create a soft, stretchy, and somewhat sticky dough; you may not need it all.

Switch the attachment to the dough hook and knead for 5-8 minutes, until the dough has a glossy sheen and no longer sticks to the bowl.  You may need to add a sprinkle of flour to the bowl if the dough is excessively sticky.

Most importantly, the dough should pass the windowpane test.  Test the dough by stretching a lump of it between the thumb and forefinger of each hand.  The dough should stretch until translucent without breaking; if not, knead for a minute longer and check again.

In a medium saucepan, melt the butter and add the sugar, maple syrup, and milk.  Stir until the sugar has fully dissolved, then let the mixture boil for a couple minutes.

Turn out the dough onto a lightly floured surface and punch it down all over to knock out the gas pockets, then roll the dough to a 15x18-inch rectangle.

Brush the dough with the melted butter, then stir together the brown sugar and cinnamon until thoroughly mixed and sprinkle evenly over top.

Tightly roll up the dough from one of the short ends and pinch the seam to seal.

Cut off the ends with a piece of stout thread by placing the thread under the log and pulling it tight to make a loop.  Keep tightening the loop until it cuts through the dough.  Slice the log into twelve equal slices and place them evenly in the prepared pan.