Lightly grease a 6-inch cast iron skillet; set aside. In a small bowl, mix together sugars, cinnamon and nuts; set aside. Place cinnamon roll pieces, swirl side up evenly spaced in pan. Brush the dough with one tablespoon of butter. Cover dough with sugar mixture and drizzle with the remaining butter. In a warm area, let rise until double in size. Bake in a preheated 325° convection oven (375° conventional oven) for 15 minutes or until light golden brown. Remove from oven. When cool, drizzle with icing if desired.