Mix the pumpkin pie filling and pour into the prepared 9x9 pan. Bake until the center is slightly wobbly and the edges are firm, about 50 to 60 minutes.
Remove from oven and cool on a rack. Chill in the refrigerator.
To serve, break the large graham crackers into 4 pieces. Slice the pumpkin custard to fit the graham crackers and set the custard pieces on top. Add a dollop of whipped cream and sprinkle some cinnamon on top. If you want to use ginger snaps, use the #60 scoop to put some custard on top of the cookie, then dollop with the whipped cream and sprinkle with the cinnamon.
You can find this recipe at https://andreasrecipes.com.