1. Use a double boiler. This is the most effective way to keep hollandaise warm, as it prevents the sauce from coming into direct contact with the heat source. To use a double boiler, fill the bottom of a large pot with water and bring it to a simmer. Place a smaller saucepan or heatproof bowl over the simmering water, making sure that the bottom of the bowl does not touch the water. Add the hollandaise to the bowl and stir constantly until it is heated through.
2. Place the hollandaise in a thermos. A thermos is a great option if you need to keep hollandaise warm for a longer period of time. Simply pour the hollandaise into the thermos and close the lid. The hollandaise will stay warm for several hours.
3. Keep the hollandaise in a warm place. If you don't have a double boiler or a thermos, you can also keep hollandaise warm by placing it in a warm place. This could be on the back of the stove, in a warm oven, or on a heating pad. Be sure to stir the hollandaise occasionally to prevent it from separating.
4. Stir the hollandaise sauce constantly. Stirring the sauce prevents the fats in the egg yolks and butter from separating.
5. Add hot water if the sauce thickens too much. Hollandaise sauce should have a creamy consistency. If it becomes too thick, you can add some hot water to thin it out.
By following these tips, you can keep your hollandaise warm and delicious for hours.