Margarita Cupcakes With Key Lime Icing

Ingredients:

1 (18 1/4 ounce) box white cake mix (no pudding in the mix)
1 (10 ounce) can frozen margarita mix, thawed (undiluted)
3 egg whites
2 tablespoons vegetable oil
1 tablespoon grated lime zest

FOR ICING

8 tablespoons unsalted butter, softened
1 (8 ounce) package cream cheese, softened
2 tablespoons key lime juice
1 teaspoon key lime zest or 1 teaspoon lemon zest
4 -5 cups confectioners' sugar

Directions:

1 In large bowl, combine cake mix, Margarita mix, egg whites and vegetable oil using electric mixer.

2 Stir in lime zest; mix completely.

3 Fill prepared pans 2/3 full.

4 Bake according to box directions (usually 325 degrees - be sure to check box!) 22-24 minutes or until toothpick inserted in center of cupcake comes out clean.

5 Cool in pan on cooling rack 5-8 minutes.

6 Remove cupcakes from pan; cool completely.
  

 FOR ICING:.
  

In large bowl, cream butter, cream cheese, juice and zest with electric mixer until light and fluffy.
  

Add 4 cups confectioners' sugar, one cup at a time; continue beating until light and fluffy.
  

If icing is too thin add additional confectioners' sugar 1 tablespoon at a time.
                                                 Source : food.com