Preheat oven to 350 degrees. Lightly spray a 9x13 baking pan with nonstick cooking spray. Set aside.
In a small bowl, combine baking powder, baking soda, salt and flour. Stir gently to mix.
In a large mixing bowl, cream together butter and sugars. Add in eggs, one at a time.
In 1/2 cup increments, add in flour mixture. Let each prior additional mix in before adding more.
Fold in oats, carrots, chocolate chips and raisins. Spread cookie dough into prepared pan.
Bake at 350 degrees for 20-25 minutes or until set and lightly browned. Remove from oven and let cool before slicing into bars.
For frosting, beat together cream and cheese and butter until smooth. Working in 1/4 cup increments, slowly beat in powdered sugar. Add milk, by the 1/2 Tbsp, until you reach the desired consistency. Spread on cooled cookie bars.