Prep: Lightly grease a 9x13 inch cake pan. Preheat the oven to 350º F.
Make cake: Add pumpkin, milk, sugar, eggs, pumpkin spice, cinnamon and HALF of the cake mix to the prepared cake pan and mix well. Sprinkle the remaining cake mix on top, then evenly sprinkle with pecans and evenly top with sliced butter.
Bake: Bake for 50-60 minutes or until a toothpick inserted in the middle comes out clean. Cool in the pan for at least 20 minutes before slicing to serve.