Preheat oven to 350F / 180CGrease and line a 9 x 13 inch pan with parchment paper.
In a medium bowl, sift together the flour, spices, baking soda, baking powder and salt. Set aside.
In a large bowl whisk together the oil, sugar and vanilla on a medium speed. Add the eggs one at a time, mixing well after each egg.
Fold in the flour mixture, mixing well until combined and making sure that there are no pockets of flour.
Add the carrots, and the nuts and raisins if using. Mix until just blended together.
Pour batter into the prepared cake pan and bake 40-50 minutes or until a toothpick inserted in the middle comes out clean.
Cool cake in the tin for 15 minutes, then turn out onto a cooling rack and allow to cool completely.