Preheat your oven to 350°F (175°C). Grease or line a muffin tin.
In a large bowl, whisk together the flour, baking powder, baking soda, salt, and cinnamon.
In another bowl, mix the oil, eggs, sugar, and vanilla extract until well combined.
Stir the grated carrots and apples into the wet ingredients.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Divide the batter evenly among the muffin cups.
Bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.
Allow the muffins to cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.