Instructions

1. Preheat your oven to 350 degrees Fahrenheit and line two muffin pans with paper baking liners.

2. In a bowl, blend one box of white cake mix, 3/4 cup key lime juice, 1/4 cup water, 1/3 cup oil, three eggs and 1 tsp. lime zest until the cake mix is moistened. Then beat the mixture for two minutes with a mixer on low speed or with a wire whisk.

3. Evenly divide the cake batter among the paper baking liners (about 2/3 full). Bake in the oven for 18 to 22 minutes. Insert a toothpick into the center of one of the cupcakes. If it comes out clean, your cupcakes are fully cooked. While the cupcakes are cooling, start making the frosting.

4. With a stand mixer or a hand mixer, beat 1 cup unsalted, room-temperature butter on low speed until light and fluffy.

5. Gradually add in 3/4 cup powdered sugar and 1/4 tsp. salt and continue mixing on low speed. Once all of the sugar is incorporated into the butter, increase the speed to medium and mix for about two minutes.

6. Add in 1 tsp. vanilla extract and 1 tbsp. milk and continue mixing on medium speed for about a minute or until light and fluffy. If the buttercream frosting is too thick, gradually add in more milk until you reach the desired consistency.

7. Once the cupcakes have completely cooled, spread about a tablespoon of frosting on each cupcake.