9 oz (18 Tablespoons) Margarita mix (such as Bacardi)
3 oz (6 Tablespoons) tequila
3/4 oz (1.5 Tablespoons) Grand Marnier
White cake mix
3 egg whites
2 Tbsp vegetable oil
1 Tbsp lime zest
1 recipe Lime Buttercream Icing (recipe follows)
Mix together the margarita mix, tequila, and Grand Marnier in a large glass or spouted bowl. You will use 1 1/4 cup of this in the cupcake mix. Pour the remainder over ice and enjoy the mini-rita while you're baking.
In a stand mixer, add the cake mix, egg whites, vegetable oil, lime zest, and 1 1/4 cup of the margarita mixture. Mix on low for about 30 seconds and then increase to medium speed for two minutes (the batter will still be a bit lumpy).
Spoon the batter into prepared muffin pan and bake at 350 for about 25 minutes or until a toothpick registers done in the center cupcake. Remove the pan from the oven and cook 5 minutes. Remove the cupcakes and cool completely on a baking rack.
Once the cupcakes have cooled, make the icing and ice the cupcakes.
Lime Buttercream Icing
3 cups + 3 Tbsp confectioner's sugar
1 cup unsalted butter at room temperature
1/8 tsp salt
1 Tbsp lime juice
1/4 cup granulated sugar (optional)
green food color (optional)
Add the butter, confectioner's sugar, salt, and lime juice to the stand mixer and mix on low using the paddle attachment until combined. Turn the speed to med-high until the icing is fluffy. Add the icing to a pastry bag fitted with a 2D tip and ice the cupcakes.