Preheat the oven to 350°F (175°C).
Grease or line a 12 cup muffin pan.
In a large bowl, mix together the flour, oats, granulated sugar, brown sugar, baking powder, baking soda, salt, cinnamon, ginger and nutmeg.
Stir in the raisins or sultanas. Set aside.
Crack the egg into a medium bowl and beat lightly.
Whisk in the buttermilk, oil and vanilla.
Stir in the bananas with a fork, making sure they are mashed into small chunks as you stir.
Stir the wet ingredients into the dry ingredients thoroughly.
Divide between the 12 muffin cups.
Bake for 20 to 25 minutes or until a toothpick, skewer or piece of dried spaghetti inserted in the centre of the muffins comes out clean.
Cool on a wire rack.
These muffins are delicious warm. Store any leftovers in an airtight container at room temperature and re-warm gently before serving.
Muffins may be frozen. Thaw overnight in the fridge and re-warm gently before serving.