Preheat oven to 350F. Take out a standard sized muffin tin and fill each well with a liner or grease them with butter.
Whisk together the flour, baking powder, baking soda, salt, and cinnamon. Set aside.
In a mixer on medium, cream the butter and sugar until light and fluffy, about 3 minutes, scraping down the down the sides of the bowl with a spatula a few times. Then add the eggs one at a time, mixing for 30 seconds after each addition. Scrape down the bowl again and add the sour cream and vanilla. Mix for 30 seconds more. Reduce the speed to low and mix in the carrots. Then add the flour mixture and mix until just combined with a few white streaks remaining. Give the batter a stir with your spatula and divide it among the twelve wells of the muffin tin.
Bake for 25-28 minutes, or until the cupcakes are lightly browned and a toothpick comes out clean. Let them rest for 2-3 minutes, then carefully take them out of the muffin tin and let them cool on a cooling rack. Can be made up to 2 days ahead.
Once the cupcakes are cool, it's time to make the frosting. Whip the cream cheese and butter on high until light and fluffy, 3 minutes. Add the vanilla and mix in. Add the confectioners' sugar and mix on low until combined, then increase the speed to high and beat together until smooth.
To decorate the cupcakes, either spread or pipe frosting onto them and then sprinkle the tops with a little orange zest.