Preheat the oven to 180°C / 160°C fan / gas mark 4 and line a 12-hole muffin tin with paper cases.
In a large bowl, mash the bananas until mostly smooth.
Add the vegetable oil, dairy-free milk, and vanilla extract, then stir until combined.
In a separate bowl, mix together the flour, light brown sugar, baking powder, bicarbonate of soda, cinnamon, and salt.
Add the dry ingredients to the banana mixture and stir gently until just combined. Do not overmix.
Divide the mixture evenly between the muffin cases.
Bake for 18–20 minutes, or until the muffins are golden and a skewer inserted into the centre comes out clean.
Leave to cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.