Preheat the oven to 180°C / 160°C fan / gas mark 4 and lightly grease a mini muffin tin.
In a large bowl, mix together the flour, baking powder, caster sugar, and cinnamon.
In a separate bowl or jug, whisk together the dairy-free milk, mashed banana, vanilla extract, and vegetable oil.
Pour the wet mixture into the dry ingredients and stir until just combined.
Fold in a few blueberries or dairy-free chocolate chips if using.
Spoon the mixture evenly into the mini muffin tin, filling each hole about three-quarters full.
Bake for 12–15 minutes until risen, lightly golden, and cooked through.
Leave to cool in the tin for a few minutes before transferring to a wire rack.