Preheat oven to 350°F (175°C) and line an 8x8 inch baking pan with parchment paper.

In a large mixing bowl, whisk together pumpkin puree, almond butter, maple syrup, and vanilla extract until smooth.

In a separate bowl, combine rolled oats, pumpkin pie spice, baking powder, and salt.

Gradually fold the dry ingredients into the wet mixture until fully incorporated.

Stir in the dark chocolate chips if using.

Transfer the batter to the prepared baking pan and press down firmly into an even layer.

Bake for 25 to 30 minutes, or until the edges are golden brown and the center is set.

Remove from oven and allow to cool completely in the pan before slicing into 12 bars.