1. Cream butter. Add sugar and 1/2 cup brown sugar. Cream until light and fluffy. Add eggs, 1 at a time. Beat well after each addition.
2. Combine the flour, baking powder, baking soda, cinnamon and salt.
3. Add dry ingredients alternately with buttermilk and beat well. Pour batter into a greased and floured 9x13 inch pan.
4. Combine the remaining brown sugar with walnuts, cinnamon and nutmeg. Sprinkle over the batter in pan. Refrigerate overnight.
5. In the morning, bake at 350ºF for 45 minutes or until cake springs back when touched lightly in center.
6. Save warm or cool.
7. * a substitute for buttermilk-add 1 tbsp. lemon juice or vinegar to 1 cup milk