Hollandaise sauce is best served fresh, otherwise the eggs and butter that make up the sauce separate. Another concern is overcooking, as the eggs in freshly made hollandaise are only partially cooked to begin with. Overcooking makes the sauce lumpy and ruins its delicate flavor. If you must reheat the sauce, it's best to do so within one day of preparing it; otherwise, spoilage becomes an issue. The reheated sauce goes well with eggs Benedict, asparagus shoots or crepes.
Pour the hollandaise sauce into a microwave-safe glass bowl. Stir with a whisk to recombine the sauce if it has separated.
Place the bowl in the microwave. Heat at 20 percent power for 15 seconds.
Stir the hollandaise sauce with the whisk and return it to the microwave. Continue to heat in 15-second increments, stirring at the end of each, until the sauce is warmed.
If the hollandaise sauce separates and won't recombine, whisk in a few drops of water.
If your stove top has a warmer setting, set the hollandaise sauce on it for up to two hours before serving. This prevents it from cooling in the first place so reheating isn't necessary.