Can I make a buttercream using cacao butter?
Cocoa butter isn't like regular butter as it is very hard at room temperature. It's what makes chocolate so hard when cooled, so it's not ideal for a creamy frosting. There are many other alternatives that would work better, for instance vegan butters which are designed to mimic butter's properties. Some vegetable shortenings can work as well, although they don't have much flavor.