Add the graham cracker crumbs, brown sugar and cinnamon to a large mixing bowl. Stir to combine. Then pour in the melted butter and stir to combine, making sure the butter is evenly distributed, so all of the crumbs are moist. Grease or spray a 13×9 inch rectangular baking dish with non-stick spray. Pour the graham cracker mixture into the baking dish and press it down evenly into the pan.
In a small bowl, combine cream cheese, 1 egg yolk, 1/2 tsp vanilla, 3 tablespoons sugar, and a pinch of salt till just mixed. This should still be somewhat firm and not soupy. If too loose, place in fridge till needed. In a large bowl, stir together the flour, baking soda, 1/2 teaspoon salt, and pumpkin pie spice. In a medium bowl, combine pumpkin purée, vegetable oil, 3 eggs, 1 1/4 cups sugar, and 1 tsp vanilla.
