Preheat oven to 350°F (175°C). Line a 9x13-inch baking dish with parchment or grease it.
Whisk together flour, pumpkin pie spice, baking soda, and salt in a large bowl.
Beat softened butter and sugar until fluffy. Mix in egg, pumpkin puree, and vanilla. Combine with dry ingredients and fold in chocolate chips. Spread batter into prepared dish.
Bake for 35-45 minutes until a toothpick comes out clean. Cool before slicing.
Notes
For extra flavor, sprinkle with a pinch of cinnamon before baking.