Preheat the oven to 350F. Grease and line an 8x8" pan with parchment.
Whisk together the flour, baking powder, orange zest, baking soda, and salt. Set aside.
Whisk the eggs together with the brown sugar, then add the sour cream, melted butter, milk, and vanilla. Whisk until smooth, then whisk in the shredded carrots.
Combine the wet and dry ingredients and mix until partially combined, then fold in the chopped pecans. Spread evenly into the prepared pan, and bake for 25-30 minutes, or until a cake tester comes out clean. Remove from the oven and let cool completely before frosting.
To make the frosting, cream the cream cheese and butter together in a mixer until smooth. Add the powdered sugar, orange juice, and orange zest. Slowly mix until smooth. Frost the bars in an even layer!
Recipe by The Kitchen Paper at http://c02.ddd.mwp.accessdomain.com/orange-carrot-cake-bars/