Mojito Cupcakes are inspired by the classic highball cocktail. Made with fresh mint, lime zest, and rum in the cake batter. A tall swirl of lime Swiss meringue buttercream is the crowning touch to each cake, with a sprinkle of white nonpareils to mimic the drink’s bubbly nature. This recipe calls for 1/2 cup fresh mint, which can be confusing to measure – so here’s how. Pick mint leaves from their stems and lightly pack them into a 1/2 cup measure, then chop them finely. You’ll also need 3 fresh limes for the lime zest and lime juice. However, sometimes limes from the grocery store are not juicy and too dry to yield enough juice. If this happens to you, bottled lime juice will work well as a replacement for fresh. Please note these cupcakes bake at a lower temperature of 325°F.
Preheat the oven to 325°F. Line a cupcake tin with 12 paper liners.
Whisk together the all-purpose flour, baking powder and salt in a medium bowl.
In the bowl of an electric mixer, beat the butter and sugar together until light and fluffy, about 3-5 minutes. Add eggs one at a time, beating well after each addition.
Add the rum, lime zest and chopped fresh mint. Mix well to combine.
Add the flour mixture alternating with the sour cream to the creamed mixture. Mix well after each addition. Begin and end with the flour mixture.
Portion the batter evenly between the cupcake cavities and bake for 18-20 minutes, or until a toothpick tester inserted in the center of a cupcake comes out clean.
Cool in the pans for 3 minutes, then transfer to a wire rack to cool completely. Meanwhile, prepare the lime buttercream.
Lime Buttercream
Place a saucepan filled 1/3 full of water over medium heat. Bring to a simmer.
In a large stainless-steel bowl, combine the egg whites and sugar. Set the bowl over the simmering water and cook while whisking intermittently. Cook until the mixture is hot (140-160°F) and you can no longer feel sugar granules when the mixture is rubbed between your finger and thumb. Transfer the hot mixture to the bowl of a stand mixer fitted with the whisk attachment. Beat on high speed for 10 minutes or until a thick, shiny meringue forms that holds stiff peaks. The bowl should feel cool to the touch. If it doesn’t, refrigerate the meringue in the bowl for 10 minutes. Return the bowl to the mixer and swap the whisk attachment for the paddle attachment.
Beat the room temperature butter into the meringue one cube at a time on medium-low speed, waiting to add the next cube when the previous cube disappears. The batter will deflate with the butter addition, and may even look curdled (if the butter was the slightest bit cold this happens), but this is normal. When all of the butter is added, beat the mixture on high speed until light in color and smooth, about 5 minutes.
Mix in the lime zest. With the mixer running on low speed, add in the lime juice one tablespoon at a time. Add the green food color and mix again until a consistent green hue is achieved. Scrape down the bowl and mix again briefly.
Transfer the buttercream to a piping bag fitted with a large open star piping tip, such as Ateco #849. Top each cupcake with a large swirl of the buttercream.
Immediately sprinkle on the white nonpareils. Add fresh mint sprigs to each cupcake just before serving.
Notes
What to expect: These cupcakes have wonderful, complex flavor thanks to the fresh mint in the batter. It's so different than the flavor of mint extract. These cupcakes are zesty, herbaceous, and fresh-tasting. The rum in the batter bakes out, leaving behind the flavor of rum but none of the booze. The Swiss meringue buttercream is lightly sweet and tangy with fresh lime zest. The nonpareils can be optional, but provide texture with their sugar crunch.Storage: Store leftover mojito cupcakes in an airtight container in the refrigerator for up to three days. Bring them to room temperature before serving for the best flavor and texture.