Preheat Oven: Preheat oven to 350°F. Coat a 9×13-inch baking pan with nonstick spray and set aside.
Mix Filling: In a large bowl, combine the pumpkin, evaporated milk, brown sugar, eggs, and pumpkin pie spice. Stir to combine, then pour into the prepared pan.
Add Toppings: Sprinkle the entire box of cake mix on top, followed by the crushed graham crackers or pecans, and optional toffee bits.
Add Butter: Pour the melted butter evenly over the top of the cake mix and toppings.
Bake: Bake for 45-50 minutes, until the center is set and the edges are lightly browned.
Serve: Serve warm or at room temperature.
Notes
Serve with ice cream or whipped cream for extra indulgence.
Store leftovers in an airtight container in the refrigerator