Creamy chocolate frosting

I am making a Chocolate rasberry cake this weekend. I need a recipe for a chocolate frosting that is creamy and not very sweet. I dont want to use sour cream did that before and didnt like the tang, but that is like what I am looking for. it will be a 3 layer chocolate cake with rasberry fruit filling in the center. I made one before with cocao powder and carnation milk that was good,but I lost it. Please help..Thank You..Patty