Preheat the oven to 350º Fahrenheit and grease a 9×13 pan with butter or cooking spray.
In a large bowl, whisk together the pumpkin, milk, eggs, sugar, salt, cinnamon, and pumpkin pie spice until well blended. Make sure the eggs are fully incorporated.
Pour the pumpkin batter into the prepared pan.
Sprinkle the dry cake mix over the pumpkin.
Drizzle with the melted butter.
Sprinkle the pecans on top. Then sprinkle the brown sugar over the pecans.
Bake for 15 minutes, then check the cake. Turn the pan to promote even browning.
Continue to bake, checking the cake often. If it is getting too brown, cover with foil for the remainder of baking.
The cake should bake for about 45-55 minutes or until a knife inserted in the center comes out clean.
Serve warm with ice cream or whipped cream.