Why buttercream splits, and how to rescue it
Buttercream that looks curdled or watery is usually not ruined. It is almost always a temperature or liquid problem, and it can be fixed.
The usual causes
| Cause | What happens |
|---|---|
| Butter too cold | It won’t take in liquid, so the mix looks curdled and lumpy |
| Butter too warm | It turns greasy and runny |
| Liquid added too fast | Milk, cream, flavourings or colourings can’t be absorbed |
| Acid with dairy | Lemon juice and some flavourings can make milky buttercream look split |
| Mixed temperatures | Cold milk into room-temperature butter is a common trigger |
How to fix it
- Curdled and lumpy: it is probably too cold. Gently warm the outside of the bowl, or take out a few spoonfuls, melt them briefly and beat them back in.
- Runny and greasy: it is too warm. Chill the bowl for 10 to 15 minutes, then beat again.
- Too wet: beat in a little more sifted icing sugar.
Preventing it next time
- Start with butter that is soft but still cool, and beat it until pale before adding sugar.
- Have liquids at room temperature and add them gradually.
- For lemon flavour, use finely grated zest or a concentrated flavouring rather than a lot of juice.
- Beat for longer than you think. Good buttercream needs time.
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