[Sca-cooks] On a whim: white chocolate buttercream???

[Phil Troy / G. Tacitus Adamantius]

Hullo, the list!

I found myself with some time to kill while Spouse and Evil Spawn (tm) 
are out, and made a very basic yellow cake, from no particular recipe. 
While it was baking, I made a buttercream frosting with unsalted 
butter, confectioner's sugar, etc. Knowing that the Evil Spawn (tm) 
seems to react adversely to chocolate liquor (IOW, all forms of 
chocolate other than white chocolate), I wondered how one makes a white 
chocolate buttercream. I mean, you can't use white cocoa; I suppose 
melting white chocolate into it might work.

What I finally ended up doing was making a basic vanilla buttercream, 
but with some of the butter replaced with softened cocoa butter (food 
grade, from the candy/cake supply place in Manhattan). That seems to 
work pretty well.

Does anybody know of any more obvious method? I've earned a living as a 
pastry chef, but in general baking isn't something that hugely 
interests me, so there may be something obvious that is eluding me.

Adamantius