Preheat oven to 350°F. Coat a 9×12-inch baking dish with nonstick spray and set aside.
Combine the pumpkin puree, evaporated milk, eggs, sugar, and pumpkin pie spice in a mixing bowl. Stir to combine and pour into the prepared baking dish.
Sprinkle dry cake mix evenly over the pumpkin layer, followed by your crushed graham crackers. Use the whole box of dry cake mix and make sure you have a full layer of crushed graham crackers.
Cover the whole cake with sliced butter pieces.
Bake in the preheated oven for 45-50 minutes until the center is set and the edges are lightly browned.
Serve warm or at room temperature. I prefer it at room temperature as it sets more and serves easier. Garnish as you wish and enjoy!
Follow along to learn more how to make easy pumpkin dump cake recipe.