Heat oven to 350ºF. In a large bowl, using a hand mixer on medium speed, combine pumpkin puree, canola oil, eggs, and sugar, until light and fluffy (about 3 minutes).
Add flour, baking powder, baking soda, salt, cinnamon, ginger, and nutmeg. Fold together until ingredients are completely combined.
Pour pumpkin mixture into ungreased 15x10" jelly roll pan. Bake 25 minutes or until toothpick inserted in center comes out clean. Let pan cool completely before frosting.
Meanwhile, for frosting, in a small bowl beat together cream cheese and butter just until combined (do not overmix). Add in maple extract and mix until combined. On low speed, slowly add in powdered sugar. Once combined, increase mixer speed to medium-medium high to thoroughly mix all ingredients together and frosting is smooth.
Evenly spread frosting over cooled bars. Cut and serve!
Notes
If you don't want to use maple extract in the frosting, you can substitute vanilla extract (or my favorite, vanilla bean paste) 1:1!
Like most pumpkin recipes, these bars get more moist and flavorful the longer they sit. So if you're making them for an occasion, I recommend making the day before for the best flavor!