Preheat oven to 350°F (175°C) and grease an 8x8 inch square baking pan.
In a large mixing bowl, whisk together the melted butter, granulated sugar, and brown sugar until smooth.
Whisk in the egg, vanilla extract, and pumpkin puree until fully incorporated.
In a separate medium bowl, combine flour, pumpkin pie spice, baking soda, and salt.
Slowly fold the dry ingredients into the wet ingredients until no streaks of flour remain.
Fold in 3/4 cup of the chocolate chips.
Spread the batter evenly into the prepared pan and sprinkle the remaining 1/4 cup of chocolate chips on top.
Bake for 25 to 30 minutes, or until a toothpick inserted into the center comes out clean or with moist crumbs.
Allow the bars to cool completely in the pan for at least 30 minutes to set the gooey center before slicing.