1-1/2 cups coarsely crushed pretzels
1/2 cup sugar
1/3 cup butter, melted
2 tablespoons bottled nonalcoholic margarita mix
1 box white cake mix
1-1/4 cups bottled nonalcoholic margarita mix
2 tablespoons tequila (optional)
1/3 cup oil
1 tablespoon grated lime peel (about 1 lime)
3 egg whites
1 container (8 oz) frozen whipped topping, thawed
Additional lime slices and/or green decorating sugars, if desired
Heat oven to 350°F. Grease bottom only of 13×9-inch pan with shortening and lightly.
In a medium bowl, mix pretzels, sugar, butter, and margarita mix. Spread evenly and press gently into bottom of pan. Set aside.
In a large bowl, beat cake mix, margarita mix, tequila (if using), oil, 1 tablespoon lime peel and the egg whites with electric mixer for about 2 minutes, scraping bowl occasionally. Pour batter over pretzel mixture.
Bake cake for 33 to 35 minutes or until light golden brown. Cool completely, about 2 hours. Frost with whipped topping; decorate with additional lime slices and or green sugars. Store covered in refrigerator.