In a medium bowl, combine cereal and milk and let stand for 5 minutes. Stir in egg, oil and vanilla, then carrots, apples and raisins.
In a large bowl, whisk together flour, brown sugar, baking powder, cinnamon and salt. Stir cereal mixture into dry ingredients, stirring just until moistened. Spoon batter into a greased or baking paper-lined 12-cup muffin tin.
Bake in the centre of the oven for 20 to 25 minutes or until golden brown. Remove from oven. Cool in pan for 5 minutes and then turn out onto rack to cool completely.