Preheat oven to 325º (or 350º depending on cake mix directions)
cupcake pan for 24 cupcakes. Use cupcake liners)
1 box white cake mix (no pudding in the mix)
1-10 oz can frozen margarita mix, thawed
3 egg whites
2 Tbsp. vegetable oil
1 Tbsp grated lime zest
3 Tbsp unsalted butter, softened
3 oz cream cheese, softened
2 Tbsp lime juice
1 tsp key lime zest or 1 tsp lemon zest
1 1/2 cups confectioners' sugar
In large bowl, combine cake mix, Margarita mix, egg whites and vegetable oil using electric mixer.
Stir in lime zest, mix completely.
Fill prepared pans 2/3 full.
Bake according to box directions, 22-24 minutes or until toothpick inserted in center of cupcake comes out clean.
Cool in pans on cooling rack 5-8 minutes.
Remove cupcakes from pans, cool completely.
In large bowl, cream butter, cream cheese, juice and zest with electric mixer until light and fluffy.
Add confectioners' sugar,one cup at a time: continue beating until light and fluffy.
If icing is too thin, add additional sugar, 1 Tbsp at a time.
Can color icing w/green & yellow food dye
Can sprinkle with kosher salt.