Preheat your oven to 180°C. Grease or line a loaf tin with baking paper.
If making your own pumpkin puree, peel and chop the pumpkin, cook until soft (either steam, boil, or roast), and mash until smooth. Let it cool slightly before using.
In a large bowl, combine the pumpkin puree, cashew cream, raw sugar, olive oil, maple syrup, and apple cider vinegar. Mix until well combined.
Add the oat flour, pumpkin spice, baking powder, and salt. Stir until everything is just combined. Avoid overmixing.
Fold in the chocolate chips and/or crushed walnuts if using. Save a few to scatter on top.
Pour the batter into the prepared loaf tin and smooth the top. Scatter any reserved chocolate chips or walnuts on top.
Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean or with just a few moist crumbs.
Let it cool in the tin for at least 15 minutes before transferring to a wire rack. Try to let it cool completely before slicing, though we understand if that's not possible.