Preheat oven to 350 degrees F.
Grease a 9x13 baking dish and set aside.
Reserve one cup of the cake mix and set aside.
Place the rest of the cake mix in a mixing bowl. Crack on egg and beat it lightly, then add it to the bowl with the cake mix. Add the eight tablespoons of melted butter. Stir with a spatula until smooth. Spread the cake layer evenly in the bottom of the prepared baking dish.
With a hand or stand mixer, beat together the pumpkin, 1/2 cup granulated sugar, three eggs, evaporated milk, vanilla, cinnamon, pumpkin pie spice and cloves. Make sure it is well combined and pour it evenly over the cake layer in the baking dish.
In a clean bowl, whisk together the remaining cup of cake mix with the 1/2 cup of brown sugar, 1/2 cup of pecans and 1/4 teaspoon of salt. Blend in the softened butter with a fork until a crumbly streussel is formed.
Evenly sprinkle the pecan streussel over the top of the pumpkin layer.
Bake the cake for 50 minutes. The center will still be jiggly when you take it out of the oven.
Allow the cake to cool completely in the pan. Cover with plastic wrap and refrigerate overnight before serving.