What you will need:
-vanilla or plain cake batter
-2 limes or about 10 key limes (12 cupcakes)
-cream cheese frosting
-lime zester or fine cheese grater
-piping bag with large star tip
Zest one full lime. The lime is not fully zested if you still see green anywhere on the body of the lime (it may be too difficult to zest the tips of the lime).
Squeeze all juice from the zested lime as well as the second lime. You should have about 4 tablespoons of juice, but exact measurement is not necessary.
Mix up your cake batter and add 1 tablespoon of lime juice as well as half of the lime zest.
Line your cupcake pan with liners, fill with batter, and bake until toothpick can go in and come out clean. Let cupcakes cool to room temperature.
Once cool, poke holes all through the tops of the cupcakes. A fork is perfect for this, but you can also use a skewer or chopsticks.
Spoon an equal amount of the remaining lime juice onto the tops of each cupcake. This is technically an optional step, but it will add a kick of lime flavor to the cupcakes that is just unparalleled. Trust me, it's totally worth it!
Stir your remaining lime zest into your cream cheese frosting. If you are serving the cupcakes immediately, it is a good idea to prepare the frosting ahead of time so that the lime zest has time to infuse flavor into the frosting.
Add your frosting to a piping bag with a large star tip and swirl the frosting onto the cupcakes.