Cream Cheese Frosted Carrot Cake Bars

1 package of 2 layer yellow cake mix
1/4 c milk
1/2 vegetable oil
1 tsp vanilla
1/2 tsp ground ginger
2 eggs
1 c finely shredded carrot
1/2 c raisins

frosting:
4 oz cream cheese, softened
1/4 c butter, softened
1/2 tsp vanilla extract
2 1/2 to 3 c powdered sugar

Preheat oven to 350 F.  Lightly grease and flour a 15x10x1 inch pan; set aside.  In a large bowl, combine cake mix, milk, oil, vanilla, ginger, and eggs.  Beat with a mixer on medium speed until well combined.  Stir in carrot and raisins.  Pour batter into prepared pan, spreading evenly.  Bake 20-22 minutes or until top springs back when lightly touched.  Cool in pan on wire rack. 

In large bowl, combine, cream cheese, butter, and vanilla.  Gradually beat in powdered sugar until frosting is spreadable.  Frost cooled cake.  Cut into bars and serve in cupcake wrappers.