1 (18.25 ounce) box white cake mix
3 egg whites
1/2 cup water
1/3 cup vegetable oil
3/4 cup strawberry margarita mix
1 (16 ounce) container frozen whipped topping, thawed
2 tablespoons grated lime zest
Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9 x 13-inch pan.
In a large bowl, stir together cake mix, egg whites, oil, water and margarita mix. Pour batter into prepared pan. Bake for 25 minutes, or until a wooden pick inserted into the center of the cake comes out clean. Allow to cool.
Frost cooled cake with whipped topping and sprinkle lime zest over top. Refrigerate until serving.
Note from LuAnn: I fold one 6-ounce container key lime-flavored yogurt into the whipped topping before spreading it onto the cake!