Preheat the oven to 350 degrees.
Mist a 9×13 pan with baking spray and set aside.
Combine the pumpkin puree, eggs, sugars, evaporated milk, cinnamon, and pumpkin pie spice in a medium measuring bowl. Whisk to combine fully.
Pour the pumpkin mixture into the bottom of your prepared pan.
In a clean bowl, use a fork to toss the cake mix with the melted butter until the mix starts to form clumps.
Evenly spread the mix over the top of the pumpkin mixture.
Bake for 60 minutes, or until the top is golden brown.
Allow the cake to come to room temperature. Transfer to the refrigerator and chill for at least 4 hours or overnight.
Serve chilled with whipped topping.