Preheat the oven to 325 degrees.Lightly grease and flour a 9x13 baking pan.In a large bowl, combine the oil, sugars, vanilla, and eggs together and blend well with a mixer.In a separate bowl, sift together the flour, baking powder, baking soda, salt, cinnamon, and nutmeg.Gradually add the flour to the sugar and egg mixture and mix well.Stir in the grated carrots. (Add the nuts and raisins at this time if you like)Pour into prepared pan.Bake for 40-45 minutes, or until a fork comes out clean. (Check, baking time will depend on your oven)Cool after taking out of oven.For the frosting, blend together the cream cheese and butter until creamy.Gradually add the powdered sugar, then the vanilla and beat for about a minute. Scrape down the sides of the bowl and beat again.Spread over the cooled cake.