HI DJ, I love using white chocolate buttercream. I make it Swiss meringue style using the 1,2,3 ratio: 5 oz egg whites, 10 oz sugar, 15oz butter, 1 TBSP vanilla extract, and 4-6 oz melted white chocolate melted and cooled. I don’t overmix the white chocolate into the SMBC, I leave it streaky so I don’t make this ahead – only just when I’m ready to use it. If I make the SMBC ahead and freeze it, I only add the chocolate after I’ve rewhipped the bc at room temp. I use Callebaut chocolate for all my chocolate cakes and frostings. I hope this helps and works for you.