Weigh flour, combine baking powder, cinnamon, and salt in medium bowl. Add carrot and stir to combine.
In another bowl combine brown and white sugars with butter and beat until fluffy and well combined. Add eggs one at a time, beating well after each addition. Stir in vanilla. add flower/carrot mixture and buttermilk alternately to sugar/butter mixture and stir well. Spread batter into a 9 X 13 pan coated with cooking spray. Bake at 350 degrees for 28-30 minutes, until a a toothpick inserted into the center comes out clean. Cool cake on a wire rack.
For Frosting
Mix together cream cheese, butter, vanilla, salt and powdered sugar until smooth and fluffy. Spread over cake and sprinkle with pecans.