On 6Bittersweets‘ and Sharin the Ninja‘s sites they show step by step of how to make these Mojito Cupcakes. Check out their sites as well as the recipe below:
1 cup milk or soymilk
1/2 C fresh mint, roughly chopped and bruised
Zest and juice of 1 lime (about 2 Tbsp juice)
2 tsp dark rum
1 1/4 cups all-purpose flour
2 Tbsp cornstarch
3/4 tsp baking powder
1/2 tsp baking soda
1/2 tsp salt
1/3 cup canola or other neutral oil
3/4 cup sugar
Lime Rum Frosting (Recipe below)
2 more limes sliced OR fresh mint leaves, to garnish
Combine milk and mint leaves in a small pot over medium heat until hot but NOT BOILING. Remove from heat and let steep for 10 to 15 minutes. Pass the milk through a strainer to remove mint leaves, but press on the leaves to extract as much flavor as possible. Set aside to cool.
Preheat oven to 350 degrees F. Line a regular 12-cup muffin pan with baking liners. Whisk the mint-infused milk and lime juice in a measuring cup and set aside for a few minutes to get good and curdled.
In large bowl, combine the sugar and lime zest and rub thoroughly to infuse the sugar with lime flavor. Add the milk mixture, oil, and rum, if using, and beat thoroughly. Sift in the flour, cornstarch, baking powder, baking soda, and salt, and mix until no large lumps remain [small ones are okay].
Fill cupcake liners two-thirds of the way and bake for 20 to 22 minutes. Transfer to a cooling rack, and let cool completely. Pipe or spread frosting on cupcakes and garnish with lime slices.
Lime Rum Cream Cheese Frosting
1/2 cup unsalted butter (1 stick), room temperature
8 ounces cream cheese, cold and cut into 6 chunks
Pinch of salt
2 tsp dark rum
1 Tbsp lime juice
1 1/2 to 3 cups powdered sugar, sifted
1 to 2 drops green food coloring, optional
Cream the butter, sugar, and salt together just until fully combined and smooth. Scrape down the sides and bottom of the bowl to ensure even mixing. Add the cold cream cheese a chunk at a time, waiting until each is incorporated before adding the next. Add the rum and lime juice and mix just until incorporated. Taste the frosting, adding more sugar if needed. Add the food coloring, if using, one drop at a time and combining thoroughly after each, until you have the color you want.