Preheat oven to 350°F.
Grease and flour a 9x13 pan and set aside.
Whisk together the flour, baking powder, baking soda, salt, and pumpkin pie spice and set aside.
Cream together the butter, granulated sugar, and brown sugar until well incorporated (it will be like a wet sand).
Beat in eggs one at a time until incorporated.
Mix in the pumpkin puree. The mixture may look curdled but it will work itself out once you add the flour.
Stir the maple extract into the milk.
Add the dry mixture to the batter, alternating with the milk, ending with the dry mixture. Mix just until combined after each addition; do not overmix.
Pour the batter into the prepared 9x13 pan and spread evenly.
Bake until a toothpick inserted in the center comes out mostly clean with a few moist crumbs, about 30-35 minutes. I suggest checking at the 25-minute mark to see where things are.
Cool on a wire rack until completely cool before you frost.
Top with Caramel Butter Frosting or the frosting of your choice. A buttercream flavored with pumpkin spice would pair well as well.
YIELD: 12-15 servings
See make-ahead and storage notes below.