Hi, Merry Christmas, i have a quick recipe, that is 1 cup crisco, 2 stick's or parkay, but i use one butter and one parkey, 1 tablespoon of vanilla, 1 lb of con sugar, i made 3 double batches. i did put a little butter flavoring in as well, ok i'm wondering if it was the crisco i used an open one and a new one, does crisco go bad and do u referigerate sp your's, i like this frosting when i need non crusting, and add a little salt and it's not real sweet, i've never had this problem before. i added another lb of sugar still has an after taste,  Help if you can Thank's so much Diane

It might very well be the butter flavoring. I've never encountered an imitation butter flavoring that didn't smell like butter that's gone anywhere from slightly to completely rancid. (And if I can't get 100% real butter on my popcorn, I eat it dry!)

I agree with the butter flavoring causing the problem, Tried it once, hated it mostly because of the smell. Worried about the after taste but the customer was thrilled with the cake and said it was the best they have ever had. I also picked up some other orders from their friends and relatives.So it must not have been as bad as I thought.  I won't ever use it again though. Maybe the after taste is not as noticeable once it is on the cake. 

I am not familiar with the sugar you are using, what is it?

I have used a very simular recipe for yrs. with butter flavoring.  That should not be the cause of the problem unless one of the ingredients is bad.  And Yes, Crisco, flavoring and even parkay can go bad :(  Crisco does not need to be 'friged. 

If you know your butter and shortening were recently new then I would say it was the butter flavoring.  I hate Wilton's as it doesn't smell very good and I think tastes terrible.  I get butter flavor from Restaurant Depot and it is perfect.  Check your flavoring.

You probably don't need the butter flavor at all if you have butter in the recipe. That also looks like a small amount of confectioner's sugar, I usually use 1 cup of fat to 1 pound of confectioner's sugar, so you should use 2 pounds of sugar for that amount of fat.

A

AAnd crisco can get a nasty rancid taste and smell, id check that first.

My recipe for BC is 1.5 cups crisco, 1 stick butter, 2 lbs powdered sugar (10x), about a tbs vanilla, a pinch of powdered salt, and .5 c water (give or take a little depending on the consistency I'm looking for). It's sweet, but not overly sweet and holds up nicely.