Pumpkin Pie Cake

Crust: 
1 box yellow cake mix (set aside 1 cup)
1/2 c. melted butter
     - combine and press into 9x13 pan

Filling: 
3-1/2 pumpkin
1/2 c. sugar
3 eggs
1/2 c. brown sugar
2/3 c. milk
pumpkin spice (to taste)
     - beat with mixer and pour over crust

Topping: 
1 c. cake mix
1/2 c. sugar
1/2 c. margarine
     - mix until crumbly and sprinkle over the top
     - bake at 325 degrees for about 1 hour or until toothpick inserted in the middle comes out clean