I have used pineapple with regular buttercream but I don't mix it together. I first take pureed pineapple, add a little sugar and boil it until it thickens more like a jam consistency. Cool before use. Slice the cake, first spread the jam and then apply buttercream (which can be coconut flavoured). I tried mango with SMBC mixing it together and it did look curdled but tasted good.
9/11/13 at 7:21pm