Preheat the oven to 350F. Spray the inside of a 9 by 13-inch baking pan with nonstick cooking spray.
Add the pumpkin, milk, eggs, brown sugar, pumpkin pie spice, and salt to a large bowl. Whisk to combine.
Pour the pumpkin mixture into the prepared baking pan. Sprinkle the dry cake mix evenly across the top, and then sprinkle on the pecans. Drizzle the melted butter on the top, trying not to leave dry patches of cake mix.
Bake until the cake is set in the center and golden brown on the top, about 45 to 60 minutes. (If it’s starting to over-brown before it’s done cooking, cover the top with a foil tent.)
Let it sit for about 15 minutes before slicing and serving.
Notes
Be sure you use canned pumpkin puree and not pumpkin pie filling.
We used a standard-size (15.25 ounces) box of Duncan Hines Perfectly Moist Classic Yellow Cake Mix - the dry mix only. You can use a different flavored cake mix such as white, pumpkin, or spice cake if desired.
Feel free to swap out the pecans for walnuts or any type of nuts you like, or simply omit them entirely.
Store the cake with an air-tight lid or tightly covered with plastic wrap in the refrigerator for up to 3 days.
You can easily prepare, bake, cool, and chill the pumpkin dump cake in the refrigerator (covered) a day in advance.