Preheat oven to 350°F. Lightly butter a 9×13 baking dish or spray with cooking spray.
Mix all of the Pumpkin Filling ingredients together in a large bowl. Pour into the prepared baking pan.
Evenly sprinkle the dry cake mix over the Filling, breaking up any clumps with a fork. Top evenly with the pads of butter, followed by the pecans, if using.
Bake uncovered at 350 degrees F for 50-60 minutes or until the cake is golden brown and cooked through and the center is mostly set (it will set more as it cools slightly). Let stand for 15 minutes before serving. Serve WARM with vanilla ice cream or whipped cream.