CAKE: Cook carrots according to package directions until tender. Drain and mash in a large bowl. Add sugar, oil, and eggs, beat well. Mix flour, baking soda, cinnamon, and salt. Beat into carrot mixture. Stir in chopped nuts.
Pour batter into cupcake pan lined with baking cups. Bake 20 minutes or until a toothpick inserted comes out clean. Cool and frost.
FROSTING: In a large mixing bowl, beat the cream cheese and butter on low speed until combined. Gradually add the sugar, blending until the sugar is well combined. Add the orange juice and zest. Increase the mixer speed until the frosting is light and fluffy, about 1 minute. Use at once to frost your cupcakes. Garnish with chopped pecans or walnuts if desired.