I made Indydebi's buttercream and also a batch of cooked flour frosting and added the Princess cake emulsion and some vanilla to both recipes.
However, after keeping them out overnight, they taste soapy and don't have a pleasing flavor at all. Any idea on how to improve the flavor? I don't want to throw them out since I made big batches for orders today 
TIA!
I have made both of those recipes and I haven't used Princess so it's most likely the emulsion. How much did you use? You could try adding more vanilla and see if that helps, but I honestly don't know.
Toss it! I know it sucks, but I just tried a new scratch recipe last night that didn't work out, plus wasted some cute Valentine's cupcake wrappers I bought. 
Sometimes it just happens.
Princess cake emulsion is an extract that can be used instead of vanilla extract:
https://www.lorannoils.com/p-8346-princess-cake-and-cookie-bakery-emulsion.aspx
The soapy flavor probably came from the powdered sugar, I would toss any PS you have from that batch. More info at the link below:
http://www.answerbag.com/q_view/512571
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