Line a large 8 x 8-inch baking pan with parchment paper and set aside.
In a large mixing bowl, add your dry ingredients and mix well. In a microwave safe bowl or stove top, combine your nut butter with sticky sweetener and melt until combined. Pour wet mixture into the dry mixture and mix until thick and crumbly. Add pumpkin puree, starting with half a cup first. If still too crumbly, add up to an extra half-cup. Batter should be thick. Transfer to lined baking pan and refrigerate. Once cool, top with optional chocolate frosting before cutting into bars.