In a large bowl combine whisk together the wet ingredients (pumpkin, Greek yoghurt, egg, vanilla, oil). Then whisk through the brown sugar until combined.
In a separate bowl combine the dry ingredients (cinnamon, nutmeg, baking soda, plain flour and oat flour. Then use a wooden spoon to fold the dry ingredients into the wet ingredients until just combined.
Pour into the prepared loaf tin and bake in the oven for 45-50mins.