In a bowl whisk the dry ingredients, (oats, flour, baking powder)
In a blender blend the remaining ingredients (banana, spinach, oil, maple syrup, egg and milk into a green smoothie
Pour the smoothie mix into the dry ingredients
Mix with a wooden spoon
Fill a greased muffin tray with the mix, I tend to use a silicone muffin tray. From the mix, I get 9-10 large , muffins or 24 mini muffins
In a fan-forced oven bake at 160 degrees Celsius or 180 degrees C if using a standard oven. Regular muffins bake for 20-25 minutes, mini muffins bake for 15-20 minutes
Cool and serve
Store in an airtight container for 2-3 days or freeze