Preheat the oven to 350°F. Lightly spray an 8x8 inch baking dish with non-stick cooking spray and set aside.
In a large bowl, whisk together the flour, baking soda, salt, cinnamon and pumpkin pie spice until combined.
In another bowl, whisk together the oil, brown sugar, egg and pumpkin puree until smooth and well combined.
Add this mixture to the dry ingredients and stir until just combined.
Pour the batter into the prepared pan and smooth the top. Bake for 30-35 minutes, or until a toothpick inserted in the centre of the cake comes out clean.
Let the cake cool completely in the pan.
In a large bowl, with an electric mixer, whip the cream cheese and the butter until smooth and creamy.
Add the vanilla and mix until combined.
Slowly add the powdered sugar in three additions, whipping the frosting after each addition.
After all the powdered sugar is added, whip until the frosting is light and fluffy, another 1-2 minutes.
Spread onto the cooled cake and sprinkle with pecans, if desired.
I usually store this cake in the fridge, due to the cream cheese frosting, but prefer it at room temperature or even warmed up a bit - so I usually take it out of the fridge a couple of hours before serving.
The amount of cream cheese frosting listed in the recipe is slightly more than the amount shown in the photos (my husband informed me there wasn’t enough!). If you are like me though, and don’t like as much frosting, use 2 oz cream cheese, 4 tbsp butter, 1 tsp vanilla and 1 1/4 cups powdered sugar.