Preheat oven to 180℃.
Line a 12-hole muffin pan with paper liners and set aside.
In a jug or small bowl, combine buttermilk, vegetable oil, vanilla, melted butter and egg, then whisk to combine and set aside (the mixture will look curdled, that's ok).
250 ml buttermilk, 60 g salted butter, 4 tablespoons vegetable oil, 2 teaspoons vanilla extract, 1 egg
To make the cinnamon sprinkle, mix the light brown sugar and cinnamon, then set aside.
½ teaspoon ground cinnamon, 2 tablespoons light brown sugar
In a large bowl place self-raising flour, light brown sugar, caster sugar and cinnamon, and whisk together to combine.
375 g self-raising flour (self-rising flour), 150 g light brown sugar, 50 g caster sugar, ½ teaspoon ground cinnamon
Add the buttermilk mixture to the flour mixture, then fold gently until it's almost incorporated with a few streaks of flour remaining - don't overmix!
Add the raisins, and fold until incorporated and the mixture is just combined.
200 g raisins
Scoop the batter into the prepared pan, dividing it equally between the prepared muffin cups, then scatter the cinnamon sprinkle mixture over the top of each muffin.
Bake for 20 - 25 minutes, or until a skewer or toothpick inserted into the centre of a muffin comes out clean.
Remove the muffins from the tin and place on a wire rack to cool.