[header] How to get buttercream to not curdle [title] Measure the ingredients carefully and exactly. [step] Ensure that the ratio of butter to sugar to liquids or flavorings is exactly right. If you have a little too much liquid (such as milk or vanilla extract) or not enough butter, the buttercream can curdle. 
Use measuring cups and spoons or a digital scale for accuracy. [title] Limit the liquid in the buttercream.