Prepare a 12-cup fluted pan with cooking spray. Sprinkle half cup brown sugar on bottom of pan, top with walnuts; set aside. In a small bowl, combine dry pudding mix, remaining brown sugar, and cinnamon. Dip each roll in melted margarine, then roll in butterscotch mixture. Arrange rolls on top of nut mixture in pan. The pan should be filled at least half way with dough. Let rise in warm place until almost doubled in size, 1 hour. The dough should rise to just under top of rim of pan. Preheat oven to 350 and bake for 35 minutes. Immediately turn over and out of pan onto wire rack to cool completely.