1/3 cup butter
1/3 cup pineapple juice (reserve from cake)
2/3 cup granulated sugar
3 to 4 cups powdered sugar (icing sugar)
couple drops of yellow food coloring (optional)
In saucepan: combine butter, pineapple juice, and granulated sugar.
Heat until sugar is dissolved. Remove from heat and gradually beat in 3 to 4 cups sifted icing sugar. Add enough to give a good spreading consistency.
Variation: Throw in a brick of cream cheese.