Sift dry ingredients. Cream together margarine, sugar, and brown sugar until fluffy. Add eggs one at a time, beating well after each. Add dry ingredients alternately with buttermilk, beating well after each addition. Spread batter in a Pam sprayed 9 x 13 pan. Top with topping.
1/2 c. brown sugar 1/2 c. nuts
1/4 tsp. nutmeg 1/2 tsp. cinnamon
Sprinkle over batter. Refrigerate 8 hours or overnight. Bake at 350 degrees for 40 to 45 minutes or until done.