Wash the orange and blend until nice and smooth (with no large chunks).
Whisk the eggs, milk and oil and vanilla together. Add the orange.
Add the flour, sugar and baking powder and mix just until combined.
Fold in the raisins.
Pour the batter into 9 muffin cases.
Bake on 175°C / 350℉ for around 22 minutes, just until an inserted skewer comes out clean.
Allow to cool a little, but they are tastiest when still warm. Enjoy!