To make the dough combine the sourdough starter, milk, egg, butter, flour, sugar, and salt.  Mix on low speed, using a dough hook, in a stand mixer for 2-3 minutes or until a sticky dough has formed.

Cover and let stand for 20 minutes.

After 20 minutes mix the dough in the stand mixer on low speed for 1 minute.   Turn the mixer up to medium speed and knead the dough for 2-3 minutes or until it is smooth and tacky.

Cover the dough and let it rise in a warm spot for 4 hours.  During this time you will need to stretch the dough and fold it once every hour.

Meanwhile, combine all ingredients for the filling in a medium bowl.  Mix well or until the mixture resembles wet sand.  Set aside.

Turn the dough onto a lightly floured work space and gently deflate it.  Carefully roll the dough into a 14 inch by 20 inch rectangle.  

Spread the filling evenly over top of the dough leaving a half inch edge along one of the short sides.

Starting with the filling covered short edge, roll the dough into a tight log.  Make sure your roll is wrapped as tightly as possible or you will lose your filling.

Cut the log into twelve 1 ½ inch slices.   Press them into a lightly greased 9 x 13 baking dish.  

Cover the pan and allow the rolls to rise until they are puffy, about 2-3 hours.   You can also put them in the refrigerator, covered, overnight if you want to bake them the next morning.  Just take them out an hour
before you want to bake them to let them come to room temperature.

When ready to bake preheat the oven to 400 degrees.  Bake for 18-22 minutes or until golden brown.  Remove from oven and cool completely.

To make the icing whisk together the icing ingredients until smooth.  Pour over top of the cinnamon rolls and use a butter knife to smooth over top of them.