Pop the sealed container into the freezer, but don’t just toss it in like a frozen pizza. Place it flat, so it chills evenly, and keep it away from strong-smelling foods—buttercream is a scent sponge, and you do not want garlic frosting. If you’re freezing piping bags (genius move, by the way), lay them flat first, then once solid, you can stack them. I once froze a bag of stray frosting tips inside—chaos, but it worked.
Can You Frosting Freeze at Alonzo Caraway blog
How long can you keep it? Up to 3 months for the best texture, though it’ll survive longer in a pinch. After that, the butter might start to oxidise, giving it a slightly funky taste. You’ll know it’s gone bad if it smells like a science experiment. Just toss it and cry for a moment, then move on.
