Cream together one cup margarine and one cup brown sugar, which has been mixed with five teaspoons cinnamon; this is sufficient for fifty or sixty large half-slices. Trim off any burned or very dark crusts, and toast lightly on both sides. Spread with above mixture, and put back in hot oven long enough to partly melt sugar. Serve very hot. Or use finely shaved maple sugar and omit cinnamon.