Saving a broken hollandaise sauce is really easy. If you should run into that problem, just follow these easy steps:
3 tbsp cold water or white wine
2 tsp corn starch
Whisk together the corn starch and cold water or white wine in a stainless steel bowl.
Place the bowl over the heat source you used when starting the hollandaise sauce - either a double boiler or direct heat.
Whisk well until the starch mixture becomes firm and pasty.
Remove from heat and slowly whisk your broken hollandaise into the pasty mixture one tablespoon at a time.