Preheat your oven to 220C/425F/Gas mark 7 and line or lightly grease a 12 hole muffin pan and place to one side.
In a large mixing bowl add in the oats, flour, sugar, baking powder, baking soda salt & spices. Whisk it all together until well combined. Then place to one side.
In a large jug or another mixing bowl combine the oil, milk, eggs, vanilla extract, pumpkin puree and mashed banana. Vigorously mix everything together until well combined.
Pour the wet ingredients into the dry ingredients and with a gentle hand bring it all together.
Scoop the batter into your prepared muffin pan, filling each cup about 2/3rds full.
Pop the muffins in your hot oven and leave for 5 minutes then reduce the heat in your oven to 190C/375F/Gas mark 5 and bake for a further 15 minutes. Check the muffins for doneness at this point. If a pick comes out of the centre clean then your muffins are baked through if not then give them a further minute or two.
Once baked through remove your muffins from the oven and allow them to rest in their pan for 5 minutes before transferring them to a wire rack to fully cool down.
Stored in an airtight container these muffins will last up to 5 days. They also freeze well for up to 3 months.