Preheat the oven to 350 F/180 C/ gas mark 4. Lightly grease a 23 cm (9 inch) square pan and line with baking paper. Set aside.
Whisk together the flour, bicarbonate of soda, baking powder, salt and cacao until thoroughly combined. Stir in the chocolate chips and pecans.
In another large bowl combine the sugar, oil, pumpkin puree and vanilla extract and stir until thoroughly incorporated.
Pour in the flour mixture and stir just to combine. Do NOT overstir the batter.
Pour the batter into the pan, smooth out the top and bake in the centre of the oven for 45 minutes. Remove from the oven, set aside for 20 minutes then lift out of the pan with the paper and place on a cooling rack.
Once you've added the flour mixture into the batter stir just to combine. Do NOT overstir.
Use melted coconut oil instead of vegetable oil if you prefer.
The cacao can be substituted with cocoa.
Walnuts make a good substitute for pecans.
Ensure your chocolate chips are dairy free (if required).
These brownies with pumpkin are best eaten a little warm.
Store in a plastic or glass container for up to 3 days (so the brownies retain their moisture).
Freeze individual brownies in a single layer on top of a tray for 2 hours then transfer into a container and freeze for up to 3 months.