Preheat the oven to 350°F. Line an 8×8-inch baking pan with parchment paper.
In a large mixing bowl, whisk together the pumpkin purée, cashew butter, coconut sugar, maple syrup, egg, egg yolk, and vanilla extract until smooth.
Add the oat flour, rolled oats, pumpkin pie spice, cinnamon, baking soda, and salt. Stir until just combined.
Let the batter rest for 5 minutes to allow the oats to absorb some moisture.
Fold in the chocolate chips, reserving a small handful for the top.
Spread the batter evenly into the prepared baking pan. Sprinkle the remaining chocolate chips over the top.
Bake for 24–29 minutes, or until the edges are set and the center is just baked through.
Allow the bars to cool completely before slicing. Sprinkle with flaky sea salt if desired.