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 half of this mixture over cake batter; swirl mixture through batter. Sprinkle remaining half 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. ----