Preheat the oven to 375F and line muffin tins with paper liners.

In a medium bowl, stir together the flour, baking powder, cinnamon and salt.

In another bowl, whisk together the sugar, oil and eggs until thick and pale; whisk in the milk and vanilla. Add to the dry ingredients along with the grated apple and stir just until combined.

Divide the batter between 11-12 muffin tins, almost filling them. Bake for 25 minutes, or until pale golden and springy to the touch. Tip the muffins in their tins to help them cool.