For the dough, combine the sugar and butter in a stand mixer fitted with the dough hook attachment. Mix on low speed, adding the salt when the sugar and butter start to come together. Add the eggs and vanilla and mix on medium speed. The mixture will look chunky. 

In a medium bowl, combine the flours and yeast, then add to the sugar mixture and mix on medium to high speed. When about half of the flour is incorporated, slowly stream in the water and continue to mix until the dough comes around the hook. It will be sticky. 

Remove the dough and knead on a floured surface. Shape into a ball, put into a greased bowl and cover with a towel. Place in a warm spot (such as on top of the stove) to proof until almost doubled in size, about 1 hour. 

Meanwhile, prepare the sugars for the filling. Place the brown sugar in a small bowl and set aside. In another small bowl, stir together the granulated sugar and cinnamon and set aside. 

When the dough is ready, grease a 9-inch cake pan and set aside. On a floured surface, roll the dough into a large rectangle horizontally that is about 14 inches wide from top to bottom. (Note: it will spring back as you roll it.) Brush the melted butter on the entire surface, reserving just a little for the top. 

Sprinkle all of the brown sugar over the surface of the dough. Next, sprinkle the cinnamon-sugar mixture over the brown sugar, reserving just a little for the top. 

Using a pizza wheel, cut the dough into horizontal strips about 2 to 3 inches wide. Depending on how big your dough rectangle is, you will end up with 5 or 6 strips. Take the top strip, roll it up into a circle and place it in the center of the prepared cake pan. Working with 1 strip at a time, roll it around the center piece, building a giant cinnamon roll in the pan. (If the strips are too long to handle, cut them in half to make it easier.) 

When you've used the last strip and the cinnamon roll is formed, brush the remaining butter on top and dust with the remaining cinnamon-sugar mixture. Cover with a towel and place in a warm spot to proof again, this time for about 15 minutes. The cinnamon roll should fill up the pan. 

Meanwhile, preheat the oven to 300°F. 

When the dough is ready, bake for 40 to 50 minutes, or until a toothpick inserted in the center comes out clean.  

While the cinnamon roll bakes, make the icing. In a large measuring cup with a spout, whisk together all of the ingredients until smooth. 

When the cinnamon roll comes out of the oven, immediately pour and spread the icing over the top. The heat will melt it into the roll's folds. (The middle of the roll may deflate a bit as the icing melts in.) 

Cut into portions and enjoy!