Spray a 9 x 13 inch baking pan (I used a glass pan) with non stick cooking spray.
Combine pumpkin, evaporated milk, brown sugar, eggs, and pumpkin spice. Stir to combine.
Pour this mixture into the prepared pan and then sprinkle the dry cake mix over all. Then top with graham cracker crumbs, toffee pieces, and pecans.
Then pour the melted butter evenly over the top.
Bake for 45-50 minutes until center is set and edges are browned.
Let cool and then serve with a dollop of whipped topping on each piece.
Notes
When the cake is done, cover the pan with its top or slice the cake and store it in an airtight container on the counter at room temperature for up to 4-5 days for the best flavor.