Preheat the over to 350 degrees F.
Line an 8x8 square baking dish with parchment, letting the ends overhang to use as "handles" later.
In a medium mixing bowl, whisk together the flour, flax, pumpkin pie spice, baking soda, and salt.
In a large mixing bowl, whisk together the pumpkin purée, coconut sugar, cashew butter, and vanilla extract.
Pour the dry into the wet and stir to combine.
Add the chocolate chips and stir to incorporate. The mixture will be thick like traditional cookie dough.
Press the mixture into the prepared baking dish. Pro tip: slightly dampen your hands so the batter doesn't stick to your hands.
Bake for 22-27 minutes until a toothpick inserted in the center comes out clean.
Cool in the pan on a wire rack until cool to the touch. Using the parchment "handles" lift the whole thing out of the pan and place on the wire rack to cool completely.
Once cool, cut into squares and enjoy!
*You can use a 9x9 baking dish also. The bars will be slightly thinner, so make sure to check for doneness earlier while baking.