1 (18.25 ounce) box plain yellow cake mix
1 cup firmly packed brown sugar
1 (30 ounce) can pumpkin
1 cup butter
2/3 cup milk
1 tablespoon cinnamon
Preheat oven to 350 degrees F. Grease a 13 x 9-inch glass baking dish.
Reserve 1 cup of the cake mix. Melt 1/2 cup of the butter and mix with remaining cake mix and 1 egg. Spread in bottom of prepared baking dish.
Mix together brown sugar, milk, cinnamon, 3 eggs and pumpkin. Pour over cake mix layer.
Combine the reserved cup of cake mix, 1/2 cup brown sugar and 1/2 cup of softened margarine. Crumble over second layer and bake for 45 minutes. Refrigerate. Cut into squares to serve.
Serve with whipped cream.