Dissolve the water and yeast in a small bowl. Set it aside for later.
In the bowl of an electric mixer combine the milk, sugar, butter, salt, egg. Mix in the yeast. Slowly stir in all 4 cups of flour. Switch to the dough attachment and knead for 8 minutes or until the dough is smooth. Turn the dough out into a lightly oiled dish. Turn once to coat. Cover with plastic wrap and let rise until doubled in size.
Punch down the dough and turn onto a lightly flowered surface. Roll into a 15x10 inch rectangle. Spread your softened butter from the filling ingredients onto your rectangle. Combine the cinnamon and brown sugar in a small bowl and sprinkle over your butter.
Starting on a long end tightly roll your dough into a log. Pinch the edge of the dough to help keep it together. Slice into 12-15 pieces and place in a lightly greased baking dish (I use a 9x13). Allow to rest for 30-45 minutes or until doubled in size.
Bake at 350 degrees for 30 minutes. Combine the frosting ingredients and spread over your warm rolls.