So….the one thing I was very nervous about trying…...the Mousseline Buttercream….Worked!!! That is, it all came together the way it was supposed to. One thing is not quite right…before I even added the Vanilla….after I added the Syrup at Firm Ball Stage…the Buttercream turned beige. Not pure white. The syrup DOES have a brownish color…unless I let it go too far…It kind of has a caramel smell. It poured beautifully….but when I tasted the Buttercream it had a slightly…very slight bitter aftertaste. When its on the cake, you can’t tell. This was just a trial. I also added too much Vanilla extract. If I make another batch, can I add this batch to the new one? That question is for any Buttercream batches. If it is frozen, can I get it to room temperature, beat it, and then add it to a newer batch freshly made?
Sounds like your sugar was cooked a bit too long. What temperature did it reach?
You can definitely combine your first batch with another to balance out the flavors. If chilled or frozen, bring to room temp and then beat the two batches together.
Here’s a photo of my 248F syrup being poured into my meringue (no amber color). The second photo is what the meringue looks like after the sugar syrup is incorporated.
Click thumbnail to see full-size image