1. Preheat oven to 350 degrees. Spray a 9x13in pan and set aside. Pour and set 1 cup of dry cake mix aside for later.
2. In a large bowl, mix 1/2 cup melted dairy-free butter, remaining cake mix, and 1 egg until blended. Press the prepared mixture into the bottom of the prepared 9x13in pan.
3. In a separate bowl whip together 2 eggs, the can of pumpkin puree, pumpkin pie spice, almond milk, and 1/2 cup sugar until smooth.
4. Pour the pumpkin mixture over top of the prepared crust in the pan.
5. In a separate bowl mix together the cup of set aside cake mix, 1/4 cup remaining sugar, and cinnamon. Cut in the butter until streusel-like. Sprinkle mixture all over the top of the prepared pumpkin bars.
6. Bake for 50-55 minutes or until cooked through.
7. Remove from oven, cool, and cut. Serve with dairy-free whipped cream or cool-whip.