Margarita Cake with Key Lime Cream Cheese Frosting

1 (18.25 ounce) package white cake mix

3 egg whites

1 (10 fluid ounce) can frozen margarita mix (such as Bacardi®), thawed

2 tablespoons vegetable oil

1 tablespoon grated lime peel

1 tablespoon lime juice

1 (8 ounce) package cream cheese, softened

½ cup unsalted butter, softened

1 tablespoon grated lemon peel

1 tablespoon lime juice

5 cups confectioners sugar

Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9x13-inch cake pan.

In a large mixing bowl, beat together the cake mix, egg whites, frozen margarita mix, vegetable oil, lime zest, and 1 tablespoon lime juice. Pour the batter into the prepared pan.

Bake in the preheated oven until a toothpick inserted into the center shows moist crumbs, 30 to 35 minutes. Cake will be very moist. Cool in the pan.

To make frosting, beat the cream cheese and butter together until light and fluffy, and stir in the lemon peel and 1 tablespoon of lime juice. Beat in the confectioners sugar, 1 cup at a time, scraping the sides of the bowl thoroughly with a spatula after each addition. Spread the frosting over the cooled cake.