Preheat oven to 350F.
Line a 9 x 13 baking pan with parchment or foil. You want to leave enough of an overhang that you can easily remove the cake after it's done baking. Set aside.
In a large bowl, whisk together flour, pumpkin pie spice, baking soda, and salt. Set aside.
In a separate bowl, cream together butter and sugar until smooth, 3 to 4 minutes.
Add egg and vanilla and beat until thoroughly combined.
Add pumpkin to mixture and beat until combined.
Slowly add flour mixture, adding in thirds, mixing just until combined.
Stir in chocolate chips, reserving 1/4 cup to sprinkle on top.
Bake 35 to 40 minutes or until an inserted toothpick comes out with just a few moist crumbs.
Sprinkle reserved chocolate chips on top of the cake and let the cake cool completely in the baking pan.
Use the parchment paper or foil to lift the cake from the pan before cutting.
Store leftovers in an airtight container for up to 3 days.