Pumpkin Cake

1 package yellow cake mix (save about 1 cup)
3 eggs
1/2 cup margarine
13 oz can pumpkin
1/2 cup packed brown sugar
2/3 cup milk
1/4 cup sugar
1 tsp cinnamon
2 tbsp margarine

Combine 1 egg, cake mix, and margarine in bottom of greased 9 by 13 pan. Mix pumpkin, pumpkin spice, brown sugar, 2 eggs, and milk. Pour over top of cake mixture. Crumble 1 cup of cake mix, mixed with sugar, cinnamon, and margarine over the top of pumpkin mixture. Bake at 350 degrees for 45 to 50 minutes. Top with whipped cream. Good when served warm or cold. Serves 12.