Mix together all ingredients for cupcake batter in an electric mixer.
Use a ice cream scoop to add batter into paper lined muffin tin. Bake at 350°F per box direction for cupcakes.
Blend together softened cream cheese and butter until smooth. Gradually add in lime juice and rum. Add lime zest then add powdered sugar, 1/2 cup at a time until smooth. Refrigerate. Frost cupcakes right before serving. Refrigerate any leftovers.
If you choose to make Margarita cupcakes substitute Rum for Tequila and Mojito mix for Margarita mix -- enjoy!