Preheat oven to 350℉. Line bottom and sides of (1) 9-by-13-inch baking pan with parchment, leaving an overhang on all sides. Grease with nonstick cooking spray.
In a medium bowl, whisk together flour, pumpkin pie spice, cinnamon, baking soda, and salt; set aside.
In the bowl of a stand mixer fitted with the paddle attachment, cream butter and sugars on medium-high speed until smooth; beat in egg and vanilla until combined. Beat in pumpkin puree. Don't worry if the mixture looks curdled; it will come together.
1 cup unsalted butter, 3/4 cup granulated sugar, 3/4 cup dark brown sugar, 1 large egg, 2 teaspoons pure vanilla extract, 1 (15-ounce) can pure pumpkin puree
Reduce speed to low, and mix in dry ingredients until just combined. Fold in chocolate chips and pecans.
2 cups dark chocolate chips, 3/4 cup pecans
Spread batter evenly in prepared pan. Bake until edges begin to pull away from sides of pan and a toothpick inserted in center comes out with just a few moist crumbs attached, 35 to 40 minutes. Cool completely in pan.
Notes
Storage
Store covered at room temperature for up to 3 days.
Variations
Dark chocolate chips can be swapped for semisweet chocolate chips or white chocolate chips.