Whisk together flour, soda, baking powder, cinnamon, and salt in a small bowl. Set aside.
In a large mixing bowl, beat sugar, eggs, and oil till thick and foamy, 1-2 minutes. Add the sour cream, vanilla, and carrots and mix well. Add the dry ingredients and stir till just blended.
Fill paper lined cupcake pans half full. Bake at 350° for 18-20 minutes. Cool completely.
For frosting, beat together cream cheese, butter, and brown sugar till smooth. Let sit for 5-10 minutes till brown sugar dissolves completely. Add vanilla, salt, and enough powdered sugar to make a frosting thick enough to pipe. Use a large star tip to frost cupcakes.