Preheat the oven to 350 degrees Fahrenheit (175 degrees Celsius) and grease an 8x8 inch baking pan or line it with parchment paper.
In a large mixing bowl, whisk together the oat flour, baking soda, salt, and pumpkin pie spice until well combined.
In a medium bowl, combine the pumpkin puree, maple syrup, melted coconut oil, eggs, and vanilla extract; whisk until smooth.
Pour the wet ingredient mixture into the dry ingredients and stir with a spatula until just combined.
Fold in 1/3 cup of the dark chocolate chips into the batter.
Spread the batter evenly into the prepared baking pan and sprinkle the remaining chocolate chips on top.
Bake for 22 to 25 minutes, or until a toothpick inserted into the center comes out clean.
Remove the pan from the oven and allow the bars to cool completely on a wire rack before slicing into 16 squares.