Mix the butter, powdered sugar, and
1/2 cup of the puree until smooth in your mixer (I looooove my
Bosch mixer for this and
for so many things it's handy for in the kitchen). Add more puree if needed until it's a good consistency. If you add too much, just add a bit more powdered sugar. If it's too dry, add more puree or a little milk or cream until it's just right.