Hollandaise is actually two separate emulsions - mixtures of fat-based and water-based substances. First you have eggs and water, whisked together over heat. Then you have a butter-yolk/water emulsion. Breaking most typically occurs when you add the butter too quickly. You can fix it by beating the broken sauce together slowly with an egg yolk that's been whisked with a tablespoon of cold water. The same principle works for broken ganache - just chill half the ganache then reheat the remaining half and beat the two together.











