Mix the sugar and the cinnamon in a bowl and stir until well blended. Cut each biscut into four pieces. Put several pieces at a time into the sugar mixture and coat well. Arrange the biscut pieces in the bundt pan. At this time you can sprinkle nuts on top (optional). Melt the margarine and add the brown sugar and stir until completely blended. Pour the brown sugar and margarine mixture on top and bake in a preheated 350 degrees oven for approximatley 30 minutes.