Preheat oven to 350 degrees and spray a 13 x 9 pan with cooking oil spray.
In a bowl, whisk pumpkin, milk, brown sugar, eggs, pumpkin pie spice, cinnamon, and salt until combined. Pour into pan.
Sprinkle dry cake mix over the entire surface using a spoon to carefully spread it to the edges.
Top with cubed butter evenly over the cake mix. Sprinkle on the pecans.
Bake for 1 hour. Cool completely before cutting into squares. Refrigerate after serving.
*You can serve with a dollop of whipped cream.
