Preheat oven to 350 degrees. In a large bowl, cream together together oil, eggs, sugar and pumpkin.
Mix in the flour, baking powder, baking soda, salt and spices.
Pour mixture into a greased 12 x 17 jelly roll pan.
Bake at 350 for 25-30 minutes. Allow to cool completely.
Meanwhile, prepare the cream cheese frosting. In the bowl of an electric mixer fitted with the paddle attachment, or in a large bowl with a hand mixer, beat cream cheese and butter together until smooth. Add maple syrup, vanilla, and powdered sugar; continue beating until well combined and smooth.
Spread frosting evenly over pumpkin bars, and cut into squares.
Optionally, top with candied pecans.
Candied Pecans: Melt 1 tablespoon butter in 12 inch skillet. Add 1 tablespoon dark brown sugar, and 1 tablespoon pure maple syrup, stir and cook over medium heat until it begins to bubble and sugar is dissolved. Add pecans, toss and stir for about two minutes. Spread pecans on a parchment lined cookie sheet in a single layer, bake at 350 for 6 to 8 minutes, until golden brown. Allow to cool completely.