Spray a 9x13" baking pan with cooking spray. Set aside.
For the filling: With a hand mixer blend together softened cream cheese, sugar, egg, and vanilla until smooth. Set aside.
For the batter: Combine the pumpkin, sugar, egg and oil in medium mixing bowl and mix until well combined.
Stir in flour, pumpkin pie spice, baking powder, baking soda, and salt. Mix well to combine.
Pour batter into prepared baking dish, and spread to cover bottom of pan.
Add dollops of the cream cheese mixture over the batter. Cut through the batter with a knife to make a marbled effect w/ the cream cheese mixture in an up and down pattern. Repeat going the other way. When marbling make sure you don't go all the way to the bottom of the pan. Sprinkle with the chopped pecans if desired.
Bake for 25 - 28 minutes or until toothpick inserted in the center comes out clean.
Cool an cut into squares. Store in the refrigerator.
Notes
If you don't have Pumpkin Pie Spice you can make your own. The substitute for 1 1/2 teaspoons of Pumpkin Pie Spice in this recipe is: 3/4 teaspoon cinnamon, 1/4 teaspoon nutmeg, 1/4 teaspoon ginger, 1/8 teaspoon allspice.Source: Just a Pinch