Cream margarine and sugar until light and fluffy. Add eggs and sour cream; mix well. Combine flour, baking powder, soda, salt and nutmeg. Add to batter, and mix well. Pour batter into greased and floured 9x13-inch baking pan. Combine brown sugar, pecans and cinnamon; mix well. Sprinkle 1/2 of this mixture over cake batter; swirl mixture through batter. Sprinkle remaining 1/2 mixture evenly over cake batter. Cover and chill ovenight. Uncover and bake in preheated 350 degree oven for 35 to 45 minutes, or until cake tests done with a toothpick. ----