I've already posted the recipe for the strawberry cupcakes, but here's the recipe for the kiwi frosting.
Ingredients
Puree of 1.5 ripe kiwis (about 1/2 a cup)
1 stick of butter
Around 3 cups of powdered sugar
1/2 t vanilla
1-2 teaspoons of salt
Procedure
1. Whip the butter, add the kiwi puree, vanilla.
2. Continue to add the powdered sugar 1/2 cup at a time until you reach the consistency of frosting that you want. Add 1 teaspoon of salt, mix and decide if you want to add more. The salt enhances the kiwi flavor while combating the tartness.